Solution-processed perovskite solar cells

Abstract

Perovskite solar cells (PSCs) have emerged as one of the most promising candidates for photovoltaic applications. Low-cost, low-temperature solution processes including coating and printing techniques makes PSCs promising for the greatly potential commercialization due to the scalability and compatibility with large-scale, roll-to-roll manufacturing processes. In this review, we focus on the solution deposition of charge transport layers and perovskite absorption layer in both mesoporous and planar structural PSC devices. Furthermore, the most recent design strategies via solution deposition are presented as well, which have been explored to enlarge the active area, enhance the crystallization and passivate the defects, leading to the performance improvement of PSC devices.

Keywords

perovskite solar cells / mesoporous structure / planar structure / solution process / large-scale deposition techniques

References

[1] GrätzelM. The light and shade of perovskite solar cells [J]. Nature Materials, 2014, 13(9): 838-842

[2] WehrenfennigC, EperonG E, JohnstonM B, SnaithH J, HerzL M. High charge carrier mobilities and lifetimes in organolead trihalide perovskites [J]. Advanced Materials, 2014, 26(10): 1584-1589

[3] ChenQ, ZhouH-p, FangY-h, StiegA Z, SongT B, WangH H, XuX-b, LiuY-s, LuS-r, YouJ-b, SunP-y, MckayJ, GoorskyM S, YangY. The optoelectronic role of chlorine in CH₃NH₃PbI₃(Cl)-based perovskite solar cells [J]. Nature Communications, 2015, 6(1): 1-9

[4] XingG-c, MathewsN, SunS-y, LimS S, LamY M, GrätzelM, MhaisalkarS, SumT C. Long-range balanced electron- and hole-transport lengths in organic-inorganic CH₃NH₃PbI₃ [J]. Science, 2013, 342(6156): 344-347

[5] DongQ-f, FangY-j, ShaoY-c, MulliganP, QiuJ, CaoL, HuangJ-s. Electron-hole diffusion lengths >175 µm in solution-grown CH₃NH₃PbI₃ single crystals [J]. Science, 2015, 347(6225): 967-970

[6] NohJ H, ImS H, HeoJ H, MandalT N, SeokSII.. Chemical management for colorful, efficient, and stable inorganic–organic hybrid nanostructured solar cells [J]. Nano Letters, 2013, 13(4): 1764-1769

[7] JeonN J, NohJ H, YangW S, KimY C, RyuS, SeoJ, SeokSII.. Compositional engineering of perovskite materials for high-performance solar cells [J]. Nature, 2015, 517(7535): 476-480

[8] LinQ-q, ArminA, NagiriR C R, BurnP L, MeredithP. Electro-optics of perovskite solar cells [J]. Nature Photonics, 2015, 9(2): 106-112

[9] YangY, YangM-j, MooreD T, YanY, MillerE M, ZhuK, BeardM C. Top and bottom surfaces limit carrier lifetime in lead iodide perovskite films [J]. Nature Energy, 2017, 2(2): 1-7

[10] KojimaA, TeshimaK, ShiraiY, MiyasakaT. Organometal halide perovskites as visible-light sensitizers for photovoltaic cells [J]. Journal of the American Chemical Society, 2009, 131(17): 6050-6051

[11] EtgarL, GaoP, XueZ-s, PengQ, ChandiranA K, LiuB, NazeeruddinM K, GrätzelM. Mesoscopic CH₃NH₃PbI₃/TiO₂ heterojunction solar cells [J]. Journal of the American Chemical Society, 2012, 134(42): 17396-17399

[12] JiangQ, ZhaoY, ZhangX-w, YangX-l, ChenY, ChuZ-m, YeQ-f, LiX-x, YinZ-g, YouJ-b. Surface passivation of perovskite film for efficient solar cells [J]. Nature Photonics, 2019, 13(4): 460-466

[13] KimM-J, KimG-H, LeeT-K, ChoiI-W, ChoiH-W, JoY-H, YoonY-J, KimJ-W, LeeJ-Y, HuhD-H, LeeH-O, KwakS-K, KimJ-Y, KimD-S. Methylammonium chloride induces intermediate phase stabilization for efficient perovskite solar cells [J]. Joule, 2019, 3(9): 2179-2192

[14] YooJ J, WiegholdS, SponsellerM C, ChuaM R, BertramS N, HartonoN T P, TresbackJ S, HansenE C, Correa-BaenaJ P, BulovićV, BuonassisiT, ShinS S, BawendiM G. An interface stabilized perovskite solar cell with high stabilized efficiency and low voltage loss [J]. Energy & Environmental Science, 2019, 12(7): 2192-2199

[15] JeonN J, NaH J, JungE H, YangT Y, LeeY G, KimG J, ShinH W, SeokSII, LeeJ M, SeoJ W. A fluorene-terminated hole-transporting material for highly efficient and stable perovskite solar cells [J]. Nature Energy, 2018, 3(8): 682-689

[16] JungE H, JeonN J, ParkE Y, MoonC S, ShinT J, YangT Y, NohJ H, SeoJ W. Efficient, stable and scalable perovskite solar cells using poly(3-hexylthiophene) [J]. Nature, 2019, 567(7749): 511-515

[17] Photovoltaic Research, NREL. Best research-cell efficiency chart [EB/OL] [2019-10-24]. https://www.nrel.gov/pv/cell-efficiency.html.

[18] HowardI A, AbzieherT, HossainI M, EggersH, SchackmarF, TernesS, RichardsB S, LemmerU, PaetzoldU W. Coated and printed perovskites for photovoltaic applications [J]. Advanced Materials, 2019, 31(26): 1806702

[19] LiZ, KleinT R, KimD H, YangM-j, BerryJ J, Van HestM F A M, ZhuK. Scalable fabrication of perovskite solar cells [J]. Nature Reviews Materials, 2018, 3418017

[20] SwartwoutR, HoerantnerM T, BulovićV. Scalable deposition methods for large-area production of perovskite thin films [J]. Energy & Encironmental Materials, 2019, 22119-145

[21] WangP, WuY-h, CaiB, MaQ-s, ZhengX-j, ZhangW-h. Solution-processable perovskite solar cells toward commercialization: Progress and challenges [J]. Advanced Functional Materials, 2019, 29(47): 1807661

[22] YouJ-b, HongZ-r, YangY M, ChenQ, CaiM, SongT B, ChenC C, LuS-r, LiuY-s, ZhouH-p, YangY. Low-temperature solution-processed perovskite solar cells with high efficiency and flexibility [J]. ACS Nano, 2014, 821674-1680

[23] YouJ-b, YangY M, HongZ-r, SongT B, MengL, LiuY-s, JiangC-y, ZhouH-p, ChangW H, LiG, YangY. Moisture assisted perovskite film growth for high performance solar cells [J]. Applied Physics Letters, 2014, 105(18): 183902

[24] MengL, YouJ-b, GuoT-F, YangY. Recent advances in the inverted planar structure of perovskite solar cells [J]. Accounts of Chemical Research, 2016, 491155-165

[25] DocampoP, BallJ M, DarwichM, EperonG E, SnaithH J. Efficient organometal trihalide perovskite planar-heterojunction solar cells on flexible polymer substrates [J]. Nature Communications, 2013, 4(1): 1-6

[26] BurschkaJ, PelletN, MoonS J, Humphry-BakerR, GaoP, NazeeruddinM K, GrätzelM. Sequential deposition as a route to high-performance perovskite-sensitized solar cells [J]. Nature, 2013, 499(7458): 316-319

[27] SalibaM, MatsuiT, DomanskiK, SeoJ Y, UmmadisinguA, ZakeeruddinS M, Correa-BaenaJ P, TressW R, AbateA, HagfeldtA, GrätzelM. Incorporation of rubidium cations into perovskite solar cells improves photovoltaic performance [J]. Science, 2016, 354(6309): 206-209

[28] MeiA-y, LiX, LiuL-f, KuZ-l, LiuT-f, RongY-g, XuM, HuM, ChenJ-z, YangY, GrätzelM, HanH-w. A hole-conductor–free, fully printable mesoscopic perovskite solar cell with high stability [J]. Science, 2014, 345(6194): 295-298

[29] XuL, WanF, RongY-g, ChenH, HeS, XuX-m, LiuG, HanH-w, YuanY-b, YangJ-l, GaoY-l, YangB-c, ZhouC-h. Stable monolithic hole-conductor-free perovskite solar cells using TiO₂ nanoparticle binding carbon films [J]. Organic Electronics, 2017, 45: 131-138

[30] ChenH, LiK-m, LiuH, GaoY-l, YuanY-b, YangB-c, ZhouC-h. Dependence of power conversion properties of hole-conductor-free mesoscopic perovskite solar cells on the loading of perovskite crystallites [J]. Organic Electronics, 2018, 61: 119-124

[31] LiK-m, ChenH, LiuH, YuanY-b, GaoY-l, YangB-c, ZhouC-h. Dependence of power conversion properties of the hole-conductor-free mesoscopic perovskite solar cells on the thickness of carbon film [J]. Organic Electronics, 2018, 62: 298-303

[32] LiuH, YangB-c, ChenH, LiK-m, LiuG, YuanY-b, GaoY-l, ZhouC-h. Efficient and stable hole-conductor-free mesoscopic perovskite solar cells using SiO₂ as blocking layer [J]. Organic Electronics, 2018, 58: 69-74

[33] GiordanoF, AbateA, Correa BaenaJ P, SalibaM, MatsuiT, ImS H, ZakeeruddinS M, NazeeruddinM K, HagfeldtA, GräetzelM. Enhanced electronic properties in mesoporous TiO₂ via lithium doping for high-efficiency perovskite solar cells [J]. Nature Communications, 2016, 7(1): 1-6

[34] KimD H, HanG S, SeongW M, LeeJ W, KimB J, ParkN G, HongK S, LeeS W, JungH S. Niobium doping effects on TiO₂ mesoscopic electron transport layer-based perovskite solar cells [J]. Chem Sus Chem, 2015, 8(14): 2392-2398

[35] LiuJ, WuY-z, QinC-j, YangX-d, YasudaT, IslamA, ZhangK, PengW-q, ChenW, HanL-y. A dopant-free hole-transporting material for efficient and stable perovskite solar cells [J]. Energy & Environmental Science, 2014, 7(9): 2963-2967

[36] SidhikS, Cerdan PasaránA, EsparzaD, López LukeT, CarrilesR, De La RosaE. Improving the optoelectronic properties of mesoporous TiO₂ by cobalt doping for high-performance hysteresis-free perovskite solar cells [J]. ACS Applied Materials & Interfaces, 2018, 10(4): 3571-3580

[37] ZhaoC, ChenB-b, QiaoX-f, LuanL, LuK, HuB. Revealing underlying processes involved in light soaking effects and hysteresis phenomena in perovskite solar cells [J]. Advanced Energy Materials, 2015, 5(14): 1500279

[38] LeeM M, TeuscherJ, MiyasakaT, MurakamiT N, SnaithH J. Efficient hybrid solar cells based on meso-superstructured organometal halide perovskites [J]. Science, 2012, 3386107643-647

[39] JiangQ, ZhangX-w, YouJ-b. SnO₂: A wonderful electron transport layer for perovskite solar cells [J]. Small, 2018, 14(31): 1801154

[40] EperonG E, BurlakovV M, DocampoP, GorielyA, SnaithH J. Morphological control for high performance, solution-processed planar heterojunction perovskite solar cells [J]. Advanced Functional Materials, 2014, 241151-157

[41] EperonG E, StranksS D, MenelaouC, JohnstonM B, HerzL M, SnaithH J. Formamidinium lead trihalide: A broadly tunable perovskite for efficient planar heterojunction solar cells [J]. Energy & Environmental Science, 2014, 7(3): 982-988

[42] HeoJ H, SongD H, HanH J, KimS Y, KimJ H, KimD, ShinH W, AhnT K, WolfC, LeeT W, ImS H. Planar CH₃NH₃PbI₃ perovskite solar cells with constant 17.2% average power conversion efficiency irrespective of the scan rate [J]. Advanced Materials, 2015, 27(22): 3424-3430

[43] XuJ-x, BuinA, IpA H, LiW, VoznyyO, CominR, YuanM-j, JeonS, NingZ-j, McdowellJ J, KanjanaboosP, SunJ P, LanX-z, QuanL-n, KimD H, HillI G, MaksymovychP, SargentE H. Perovskite–fullerene hybrid materials suppress hysteresis in planar diodes [J]. Nature Communications, 2015, 6(1): 1-8

[44] LiL, ChenY-h, LiuZ-h, ChenQ, WangX-d, ZhouH-p. The additive coordination effect on hybrids perovskite crystallization and high-performance solar cell [J]. Advanced Materials, 2016, 28(44): 9862-9868

[45] LiS-s, ChangC-h, WangY-c, LinC-w, WangD-y, LinJ C, ChenC C, SheuH S, ChiaH-c, WuW-r, JengU S, LiangC-t, SankarR, ChouF-c, ChenC-w. Intermixing-seeded growth for high-performance planar heterojunction perovskite solar cells assisted by precursorcapped nanoparticles [J]. Energy & Environmental Science, 2016, 9(4): 1282-1289

[46] JengJ-y, ChiangY-f, LeeM-h, PengS-r, GuoT-f, ChenP, WenT-c. CH₃NH₃PbI₃ perovskite/fullerene planar-heterojunction hybrid solar cells [J]. Advanced Materials, 2013, 25(27): 3727-3732

[47] HyuckH J, Ji HanH, KimD, Kyu AhnT, HyukI M S. Hysteresis-less inverted CH₃NH₃PbI₃ planar perovskite hybrid solar cells with 18.1% power conversion efficiency [J]. Energy & Environmental Science, 2015, 8(5): 1602-1608

[48] Turren-CruzS H, SalibaM, MayerM T, Juárez-SantiestebanH, MathewX, NienhausL, TressW, ErodiciM P, SherM J, BawendiM G, GrätzelM, AbateA, HagfeldtA, CorreabaenaJ P. Enhanced charge carrier mobility and lifetime suppress hysteresis and improve efficiency in planar perovskite solar cells [J]. Energy & Environmental Science, 2018, 11(1): 78-86

[49] WangQ, ShaoY-c, DongQ-f, XiaoZ-g, YuanY-b, HuangJ-s. Large fill-factor bilayer iodine perovskite solar cells fabricated by a low-temperature solution-process [J]. Energy & Environmental Science, 2014, 7(7): 2359-2365

[50] BiD, MoonS J, HäggmanL, BoschlooG, YangL, JohanssonE M J, NazeeruddinM K, GrätzelM, HagfeldtA. Using a two-step deposition technique to prepare perovskite (CH₃NH₃PbI₃) for thin film solar cells based on ZrO₂ and TiO₂ mesostructures [J]. RSC Advances, 2013, 3(41): 18762

[51] ChenQ, ZhouH-p, HongZ-r, LuoS, DuanH-s, WangH-h, LiuY-s, LiG, YangY. Planar heterojunction perovskite solar cells via vapor-assisted solution process [J]. Journal of the American Chemical Society, 2014, 1362622-625

[52] DocampoP, HanuschF C, StranksS D, DöblingerM, FecklJ M, EhrenspergerM, MinarN K, JohnstonM B, SnaithH J, BeinT. Solution deposition-conversion for planar heterojunction mixed halide perovskite solar cells [J]. Advanced Energy Materials, 2014, 4(14): 1400355

[53] XiaoZ-g, BiC, ShaoY-c, DongQ-f, WangQ, YuanY-b, WangC-g, GaoY-l, HuangJ-s. Efficient, high yield perovskite photovoltaic devices grown by interdiffusion of solution-processed precursor stacking layers [J]. Energy & Environmental Science, 2014, 782619-2623

[54] BiC, WangQ, ShaoY-c, YuanY-b, XiaoZ-g, HuangJ-s. Non-wetting surface-driven high-aspect-ratio crystalline grain growth for efficient hybrid perovskite solar cells [J]. Nature Communications, 2015, 6(1): 7747

[55] WangQ, DongQ-f, LiT, GruvermanA, HuangJ-s. Thin insulating tunneling contacts for efficient and water-resistant perovskite solar cells [J]. Advanced Materials, 2016, 28316734-6739

[56] KimJ H, WilliamsS T, ChoN, ChuehC C, JenA K Y. Enhanced environmental stability of planar heterojunction perovskite solar cells based on blade-coating [J]. Advanced Energy Materials, 2015, 5(4): 1401229

[57] BarrowsA T, PearsonA J, KwakC K, DunbarA D F, BuckleyA R, LidzeyD G. Efficient planar heterojunction mixed-halide perovskite solar cells deposited via spray-deposition [J]. Energy & Environmental Science, 2014, 792944-2950

[58] VakD, HwangK, FaulksA, JungY S, ClarkN, KimD Y, WilsonG J, WatkinsS E. 3D printer-based slot-die coater as a lab-to-fab translation tool for solution-processed solar cells [J]. Advanced Energy Materials, 2015, 5(4): 1401539

[59] WuH, ZhangC-j, DingK-x, WangL-j, GaoY-l, YangJ-l. Efficient planar heterojunction perovskite solar cells fabricated by in-situ thermal-annealing doctor blading in ambient condition [J]. Organic Electronics, 2017, 45: 302-307

[60] PengY-y, ChengY-d, WangC-h, ZhangC-j, XiaH-y, HuangK-q, TongS-c, HaoX-t, YangJ-l. Fully doctor-bladed planar heterojunction perovskite solar cells under ambient condition [J]. Organic Electronics, 2018, 58153-158

[61] HuQ, WuH, SunJ, YanD-h, GaoY-l, YangJ-l. Large-area perovskite nanowire arrays fabricated by large-scale roll-to-roll micro-gravure printing and doctor blading [J]. Nanoscale, 2016, 8(9): 5350-5357

[62] LiH-y, GuoH, TongS-c, HuangK-q, ZhangC-j, WangX-f, ZhangD, ChenX-h, YangJ-l. High-performance supercapacitor carbon electrode fabricated by large-scale roll-to-roll micro-gravure printing [J]. Journal of Physics D: Applied Physics, 2019, 52(11): 115501

[63] TongS-c, WuH, ZhangC-j, LiS-g, WangC-h, ShenJ-q, XiaoS, HeJ, YangJ-l, SunJ, GaoY-l. Large-area and high-performance CH₃NH₃PbI₃ perovskite photodetectors fabricated via doctor blading in ambient condition [J]. Organic Electronics, 2017, 49: 347-354

[64] DengY-h, ZhengX-p, BaiY, WangQ, ZhaoJ-j, HuangJ-s. Surfactant-controlled ink drying enables high-speed deposition of perovskite films for efficient photovoltaic modules [J]. Nature Energy, 2018, 3(7): 560-566

[65] DengY-h, DongQ-f, BiC, YuanY-b, HuangJ-s. Air-stable, efficient mixed-cation perovskite solar cells with Cu electrode by scalable fabrication of active layer [J]. Advanced Energy Materials, 2016, 6(11): 1600372

[66] TangS, DengY-h, ZhengX-p, BaiY, FangY-j, DongQ-f, WeiH-t, HuangJ-s. Composition engineering in doctor-blading of perovskite solar cells [J]. Advanced Energy Materials, 2017, 7181700302

[67] WuW-q, YangZ-b, RuddP N, ShaoY-c, DaiX-z, WeiH-t, ZhaoJ-j, FangY-j, WangQ, LiuY, DengY-h, XiaoX, FengY-x, HuangJ-s. Bilateral alkylamine for suppressing charge recombination and improving stability in blade-coated perovskite solar cells [J]. Science Advances, 2019, 53eaav8925

[68] WuW-q, WangQ, FangY-j, ShaoY-c, TangS, DengY-h, LuH-d, LiuY, LiT, YangZ-b, GruvermanA, HuangJ-s. Molecular doping enabled scalable blading of efficient hole-transport-layer-free perovskite solar cells [J]. Nature Communications, 2018, 911625

[69] JungM, JiS G, KimG, SeokSII.. Perovskite precursor solution chemistry: From fundamentals to photovoltaic applications [J]. Chemical Society Reviews, 2019, 4872011-2038

[70] HwangK, JungY S, HeoY J, ScholesF H, WatkinsS E, SubbiahJ, JonesD J, KimD Y, VakD. Toward large scale roll-to-roll production of fully printed perovskite solar cells[J]. Advanced Materials, 2015, 27(7): 1241-1247

[71] WhitakerJ B, KimD H, LarsonB W, ZhangF, BerryJ J, Van HestM F A M, ZhuK. Scalable slot-die coating of high-performance perovskite solar cells [J]. Sustainable Energy & Fuels, 2018, 2(11): 2442-2449

[72] GONG Chen-di, TONG Si-chao, HUANG Ke-qing, LI Heng-yue, HUANG Han, ZHANG Jian, YANG Jun-liang. Flexible planar heterojunction perovskite solar cells fabricated via sequential roll-to-roll microgravure printing and slot-die coating deposition [J]. Solar RRL, 2019: 1900204. DOI: https://doi.org/10.1002/solr.201900204.

[73] HeoJ H, LeeM H, JangM H, ImS H. Highly efficient CH₃NH₃PbI_3−xCl mixed halide perovskite solar cells prepared by re-dissolution and crystal grain growth via spray coating [J]. Journal of Materials Chemistry A, 2016, 4(45): 17636-17642

[74] ZhangC-j, LuoQ, WuH, LiH-y, LaiJ-q, JiG-q, YanL-p, WangX-f, ZhangD, LinJ, ChenL-w, YangJ-l, MaC-q. Roll-to-roll micro-gravure printed large-area zinc oxide thin film as the electron transport layer for solution-processed polymer solar cells [J]. Organic Electronics, 2017, 45190-197

[75] YangJ-l, VakD, ClarkN, SubbiahJ, WongW W H, JonesD J, WatkinsS E, WilsonG. Organic photovoltaic modules fabricated by an industrial gravure printing proofer [J]. Solar Energy Materials and Solar Cells, 2013, 109: 47-55

[76] TongS-c, GongC-d, ZhangC-j, LiuG, ZhangD, ZhouC-h, SunJ, XiaoS, HeJ, GaoY-l, YangJ-l. Fully-printed, flexible cesium-doped triple cation perovskite photodetector [J]. Applied Materials Today, 2019, 15: 389-397

[77] LiS-g, JiangK-j, SuM-j, CuiX-p, HuangJ-h, ZhangQ-q, ZhouX-q, YangL-m, SongY-l. Inkjet printing of CH₃NH₃PbI₃ on a mesoscopic TiO₂ film for highly efficient perovskite solar cells [J]. Journal of Materials Chemistry A, 2015, 3(17): 9092-9097

[78] EggersH, SchackmarF, AbzieherT, SunQ, LemmerU, VaynzofY, RichardsB S, Hernandez-SosaG, PaetzoldU W. Inkjet-printed micrometer-thick perovskite solar cells with large columnar grains [J]. Advanced Energy Materials, 2019, 9: 1903184

[79] RazzaS, Castro-HermosaS, Di CarloA, BrownT M. Research update: Large-area deposition, coating, printing, and processing techniques for the upscaling of perovskite solar cell technology [J]. APL Materials, 2016, 4(9): 091508

[80] HeM, LiB, CuiX, JiangB-b, HeY-j, ChenY-h, O’NeilD, SzymanskiP, Ei-SayedM A, HuangJ-s, LinZ-q. Meniscus-assisted solution printing of large-grained perovskite films for high-efficiency solar cells [J]. Nature Communications, 2017, 8116045

[81] NieW, TsaiH, AsadpourR, BlanconJ C, NeukirchA J, GuptaG, CrochetJ J, ChhowallaM, TretiakS, AlamM A, WangH L, MohiteA D. High-efficiency solution-processed perovskite solar cells with millimeter-scale grains [J]. Science, 2015, 3476221522-525

[82] YeF, ChenH, XieF-x, TangW-t, YinM-s, HeJ-j, BiE-b, WangY-b, YangX-d, HanL-y. Soft-cover deposition of scaling-up uniform perovskite thin films for high cost-performance solar cells [J]. Energy & Environmental Science, 2016, 9(7): 2295-2301

[83] CaiM-l, WuY-z, ChenH, YangX-d, QiangY-h, HanL-y. Cost-performance analysis of perovskite solar modules [J]. Advanced Science, 2017, 4(1): 1600269

[84] XiaoZ-g, DongQ-f, BiC, ShaoY-c, YuanY-b, HuangJ-s. Solvent annealing of perovskite-induced crystal growth for photovoltaic-device efficiency enhancement [J]. Advanced Materials, 2014, 26376503-6509

[85] BiC, YuanY-b, FangY-j, HuangJ-s. Low-temperature fabrication of efficient wide-bandgap organolead trihalide perovskite solar cells [J]. Advanced Energy Materials, 2015, 5(6): 1401616

[86] JeonN J, NohJ H, KimY C, YangW S, RyuS, SeokS [II.. Solvent engineering for high-performance inorganic–organic hybrid perovskite solar cells [J]. Nature Materials, 2014, 139897-903

[87] NgA, RenZ-w, HuH-l, FongP W K, ShenQ, CheungS H, QinP-l, LeeJ W, DjurišićA B, SoS K, LiG, YangY, SuryaC. A cryogenic process for antisolvent-free high-performance perovskite solar cells [J]. Advanced Materials, 2018, 30(44): 1804402

[88] XueJ-j, WangR, WangK-l, WangZ-k, YavuzI, WangY, YangY-g, GaoX-y, HuangT-y, NuryyevaS, LeeJ W, DuanY, LiaoL-s, KanerR, YangY. Crystalline liquid-like behavior: surface-induced secondary grain growth of photovoltaic perovskite thin film [J]. Journal of the American Chemical Society, 2019, 1413513948-13953

[89] ZhouZ-m, WangZ-w, ZhouY-y, PangS-p, WangD, XuH-x, LiuZ-h, PadtureN P, CuiG-l. Methylaminegas-induced defect-healing behavior of CH₃NH₃PbI₃ thin films for perovskite solar cells [J]. Angewandte Chemie International Edition, 2015, 54(33): 9705-9709

[90] YangM-j, ZhangT-y, SchulzP, LiZ, LiG, KimD H, GuoN-j, BerryJ J, ZhuK, ZhaoY-x. Facile fabrication of large-grain CH₃NH₃PbI_3−xBr_x films for high-efficiency solar cells via CH₃NH₃Br-selective Ostwald ripening [J]. Nature Communications, 2016, 712305

[91] ShaoY-c, XiaoZ-g, BiC, YuanY-b, HuangJ-s. Origin and elimination of photocurrent hysteresis by fullerene passivation in CH₃NH₃PbI₃ planar heterojunction solar cells [J]. Nature Communications, 2014, 5(1): 5784

[92] BaiY, DongQ-f, ShaoY-c, DengY-h, WangQ, ShenL, WangD, WeiW, HuangJ-s. Enhancing stability and efficiency of perovskite solar cells with crosslinkable silane-functionalized and doped fullerene [J]. Nature Communications, 2016, 7112806

[93] ZhengX-p, ChenB, DaiJ, FangY-j, BaiY, LinY-z, WeiH-t, ZengX-c, HuangJ-s. Defect passivation in hybrid perovskite solar cells using quaternary ammonium halide anions and cations [J]. Nature Energy, 2017, 2717102

[94] LinY, BaiY, FangY-j, ChenZ-l, YangS, ZhengX-p, TangS, LiuY, ZhaoJ-j, HuangJ-s. Enhanced thermal stability in perovskite solar cells by assembling 2D/3D stacking structures [J]. The Journal of Physical Chemistry Letters, 2018, 93654-658

[95] HuehC C, LiC-z, JenA K Y. Recent progress and perspective in solution-processed interfacial materials for efficient and stable polymer and organometal perovskite solar cells [J]. Energy & Environmental Science, 2015, 8(4): 1160-1189

[96] ZhouH-p, ChenQ, LiG, LuoS, SongT-b, DuanH-s, HongZ-r, YouJ-b, LiuY-s, YangY. Interface engineering of highly efficient perovskite solar cells [J]. Science, 2014, 345(6196): 542-546

[97] PathakS K, AbateA, RuckdeschelP, RooseB, GödelK C, VaynzofY, SanthalaA, WatanabeS I, HollmanD J, NoelN, SepeA, WiesnerU, FriendR, SnaithH J, SteinerU. Performance and stability enhancement of dye-sensitized and perovskite solar cells by al doping of TiO₂ [J]. Advanced Functional Materials, 2014, 24(38): 6046-6055

[98] LiuZ-h, HuJ-n, JiaoH-y, LiL, ZhengG, ChenY-h, HuangY, ZhangQ, ShenC, ChenQ, ZhouH-p. Chemical reduction of intrinsic defects in thicker heterojunction planar perovskite solar cells [J]. Advanced Materials, 2017, 29(23): 1606774

[99] TanH-r, JainA, VoznyyO, LanX-z, ArquerF P G D, FanJ Z, Quintero-BermudezR, YuanM-j, ZhangB, ZhaoY-c, FanF-j, LiP-c, QuanL-n, ZhaoY-b, LuZ-h, YangZ-y, HooglandS, SargentE H. Efficient and stable solution-processed planar perovskite solar cells via contact passivation [J]. Science, 2017, 3556326722-726

[100] UanZ-c, WuZ-w, BaiS, XiaZ-h, XuW-d, SongT, WuH-h, XuL-h, SiJ-j, JinY-z, SunB-q. Hot-electron injection in a sandwiched TiO_x–Au–TiO_x structure for high-performance planar perovskite solar cells [J]. Advanced Energy Materials, 2015, 5(10): 1500038

[101] TavakoliM M, YadavP, TavakoliR, KongJ. Surface engineering of TiO₂ ETL for highly efficient and hysteresis-less planar perovskite solar cell (21.4%) with enhanced open-circuit voltage and stability [J]. Advanced Energy Materials, 2018, 8231800794

[102] BaenaJ P C, SteierL, TressW, SalibaM, NeutznerS, MatsuiT, GiordanoF, Jesper JacobssonT, KandadaA R S, M. ZakeeruddinS, PetrozzaA, AbateA, Khaja NazeeruddinM, GrätzelM, HagfeldtA. Highly efficient planar perovskite solar cells through band alignment engineering [J]. Energy & Environmental Science, 2015, 8102928-2934

[103] RaoH S, ChenB-x, LiW-g, XuY-f, ChenH-y, KuangD-b, SuC-y. Improving the extraction of photogenerated electrons with SnO₂ nanocolloids for efficient planar perovskite solar cells [J]. Advanced Functional Materials, 2015, 25(46): 7200-7207

[104] Halvani AnarakiE, KermanpurA, SteierL, DomanskiK, MatsuiT, TressW, SalibaM, AbateA, GrätzelM, HagfeldtA, CorreabaenaJ P. Highly efficient and stable planar perovskite solar cells by solution-processed tin oxide [J]. Energy & Environmental Science, 2016, 9(10): 3128-3134

[105] WangC-h, ZhangC-j, WangS-t, LiuG, XiaH-y, TongS-c, HeJ, NiuD-m, ZhouC-h, DingK-x, GaoY-l, YangJ-l. Low–temperature processed, efficient, and highly reproducible cesium-doped triple cation perovskite planar heterojunction solar cells [J]. Solar RRL, 2018, 2(2): 1700209

[106] HuangK-q, PengY-y, GaoY-x, ShiJ, LiH-y, MoX-d, HuangH, GaoY-l, DingL-m, YangJ-l. High-performance flexible perovskite solar cells via precise control of electron transport layer [J]. Advanced Energy Materials, 2019, 9441901419

[107] HuangK-q, LiH-y, ZhangC-j, GaoY-x, LiuT-j, ZhangJ, GaoY-l, PengY-y, DingL-m, YangJ-l. Highly efficient perovskite solar cells processed under ambient conditions using in situ substrate-heating-assisted deposition [J]. Solar RRL, 2019, 331800318

[108] WangC-h, YangJ-l. Interface modification for organic and perovskite solar cells [J]. Science China Materials, 2016, 599743-756

[109] GaoY-x, DongY-n, HuangK-q, ZhangC-j, LiuB, WangS-t, ShiJ, XieH-p, HuangH, XiaoS, HeJ, GaoY-l, HattonR A, YangJ-l. Highly efficient, solution-processed CsPbI₂Br planar heterojunction perovskite solar cells via flash annealing [J]. ACS Photonics, 2018, 5(10): 4104-4110

[110] JiangQ, ZhangL-q, WangH-l, YangX-l, MengJ-h, LiuH, YinZ-g, WuJ-l, ZhangX-w, YouJ-b. Enhanced electron extraction using SnO₂ for high-efficiency planar-structure HC(NH₂)₂PbI₃-based perovskite solar cells [J]. Nature Energy, 2016, 2(1): 1-7

[111] KeW-j, ZhaoD-w, XiaoC-x, WangC-l, CimaroliA J, GriceC R, YangM-j, LiZ, JiangC-s, Al-JassimM, ZhuK, KanatzidisM G, FangG-j, YanY-f. Cooperative tin oxide fullerene electron selective layers for high-performance planar perovskite solar cells [J]. Journal of Materials Chemistry A, 2016, 4(37): 14276-14283

[112] WuW-q, ChenD-h, ChengY-b, CarusoR A. Thin films of tin oxide nanosheets used as the electron transporting layer for improved performance and ambient stability of perovskite photovoltaics [J]. Solar RRL, 2017, 1(11): 1700117

[113] YangD, YangR-x, WangK, WuC-c, ZhuX-j, FengJ-s, RenX-d, FangG-j, PriyaS, LiuS-z Frank. High efficiency planar-type perovskite solar cells with negligible hysteresis using EDTA-complexed SnO₂ [J]. Nature Communications, 2018, 911-11

[114] HU Man-man, ZHANG Luo-zheng, SHE Su-yang, WU Jian-chang, ZHOU Xian-yong, LI Xiang-nan, WANG Deng, MIAO Jun, MI Guo-jun, CHEN Hong, TIAN Yan-qing, XU Bao-min, CHENG Chun. Electron transporting bilayer of SnO₂ and TiO₂ nanocolloid enables highly efficient planar perovskite solar cells [J]. Solar RRL, 2019: 1900331. DOI: https://doi.org/10.1002/solr.201900331.

[115] HuiW, YangY-g, XuQ, GuH, FengS-l, SuZ-h, ZhangM-r, WangJ, LiX-d, FangJ-f, XiaF, XiaY-d, ChenY-h, GaoX-y, HuangW. Red-carbon-quantum-dot-doped SnO₂ composite with enhanced electron mobility for efficient and stable perovskite solar cells [J]. Advanced Materials, 2019, 91906374

[116] ZhuP-c, GuS, LuoX, GaoY, LiS-l, ZhuJ, TanH-r. Simultaneous contact and grain-boundary passivation in planar perovskite solar cells using SnO₂-KCl composite electron transport layer [J]. Advanced Energy Materials, 2019, 10(3): 1903083

[117] CHEN Jin-bo, DONG Hua, ZHANG Lin, LI Jing-rui, JIA Fu-hao, JIAO Bo, JIE Xu, HOU Xun, LIU Jian, WU Zhao-xin. Graphitic carbon nitride doped SnO₂ enabling efficient perovskite solar cells exceeding 22% [J]. Journal of Materials Chemistry A, 2020. DOI: https://doi.org/10.1039/C9TA11344D.

[118] TiwanaP, DocampoP, JohnstonM B, SnaithH J, HerzL M. Electron Mobility and injection dynamics in mesoporous ZnO, SnO₂, and TiO₂ films used in dye-sensitized solar cells [J]. ACS Nano, 2011, 565158-5166

[119] HeoJ H, LeeM H, HanH J, PatilR B, YuJ S, ImS H. Highly efficient low temperature solution processable planar type CH₃NH₃PbI₃ perovskite flexible solar cells [J]. Journal of Materials Chemistry A, 2016, 4(5): 1572-1578

[120] YangJ-l, SiempelkampB D, MosconiE, De AngelisF, KellyT L. Origin of the thermal instability in CH₃NH₃PbI₃ thin films deposited on ZnO [J]. Chemistry of Materials, 2015, 27(12): 4229-4236

[121] AzmiR, HwangS, YinW-p, KimT W, AhnT K, JangS Y. High efficiency low-temperature processed perovskite solar cells integrated with alkali metal doped ZnO electron transport layers [J]. ACS Energy Letters, 2018, 3(6): 1241-1246

[122] Mahdi TavakoliM, TavakoliR, YadavP, KongJ. A graphene/ZnO electron transfer layer together with perovskite passivation enables highly efficient and stable perovskite solar cells [J]. Journal of Materials Chemistry A, 2019, 7(2): 679-686

[123] QinM-c, MaJ-j, KeW-j, QinP-l, LeiH-w, TaoH, ZhengX-l, XiongL-b, LiuQ, ChenZ-l, LuJ-z, YangG, FangG-j. Perovskite solar cells based on low-temperature processed indium oxide electron selective layers [J]. ACS Applied Materials & Interfaces, 2016, 8(13): 8460-8466

[124] ChenP, YinX-t, QueM-d, LiuX-b, QueW-x. Low temperature solution processed indium oxide thin films with reliable photoelectrochemical stability for efficient and stable planar perovskite solar cells [J]. Journal of Materials Chemistry A, 2017, 5(20): 9641-9648

[125] YoonS, KimS J, KimH S, ParkJ S, KiH I K, JungJ W, ParkM. Solution-processed indium oxide electron transporting layers for high-performance and photo-stable perovskite and organic solar cells [J]. Nanoscale, 2017, 9(42): 16305-16312

[126] LingX-f, YuanJ-y, LiuD-y, WangY-j, ZhangY-n, ChenS, WuH-h, JinF, WuF-p, ShiG-z, TangX, ZhengJ-w, LiuS-z F, LiuZ-k, MaW-l. Room-temperature processed Nb₂O₅ as the electron-transporting layer for efficient planar perovskite solar cells [J]. ACS Applied Materials & Interfaces, 2017, 9(27): 23181-23188

[127] WangZ-h, LouJ-j, ZhengX-j, ZhangW-h, QinY. Solution processed Nb₂O₅ electrodes for high efficient ultraviolet light stable planar perovskite solar cells [J]. ACS Sustainable Chemistry & Engineering, 2019, 7(7): 7421-7429

[128] ShinS S, YangW S, YeomE J, LeeS J, JeonN J, JooY C, ParkI J, NohJ H, SeokSII.. Tailoring of electron-collecting oxide nanoparticulate layer for flexible perovskite solar cells [J]. The Journal of Physical Chemistry Letters, 2016, 7(10): 1845-1851

[129] ShinS S, YeomE J, YangW S, HurS, KimM G, ImJ, SeoJ, NohJ H, SeokSII.. Colloidally prepared la-doped BaSnO₃ electrodes for efficient, photostable perovskite solar cells [J]. Science, 2017, 356(6334): 167-171

[130] SHIN S S, SUK J H, KANG B J, YIN W P, LEE S J, NOH J H, AHN T K, ROTERMUND F, CHO I S, SEOK S II. Energy-level engineering of the electron transporting layer for improving open-circuit voltage in dye and perovskite-based solar cells [J]. Energy & Environmental Science, 2019. DOI: https://doi.org/10.1039/C8EE03672A.

[131] GuoH, ChenH-y, ZhangH-y, HuangX, YangJ, WangB-j, LiY-l, WangL-p, NiuX-b, WangZ-m. Low-temperature processed yttrium-doped SrSnO₃ perovskite electron transport layer for planar heterojunction perovskite solar cells with high efficiency [J]. Nano Energy, 2019, 591-9

[132] LiuJ, GaoC, LuoL-z, YeQ-y, HeX-l, OuyangL-q, GuoX-w, ZhuangD-m, LiaoC, MeiJ, LauW. Low-temperature, solution processed metal sulfide as an electron transport layer for efficient planar perovskite solar cells [J]. Journal of Materials Chemistry A, 2015, 3(22): 11750-11755

[133] DongJ, WuJ-h, JiaJ-b, FanL-q, LinY, LinJ-m, HuangM-l. Efficient perovskite solar cells employing a simply-processed CdS electron transport layer [J]. Journal of Materials Chemistry C, 2017, 5(38): 10023-10028

[134] XuZ, WuJ-h, YangY-q, LanZ, LinJ-m. High-efficiency planar hybrid perovskite solar cells using indium sulfide as electron transport layer [J]. ACS Applied Energy Materials, 2018, 1(8): 4050-4056

[135] YinG-n, ZhaoH, FengJ-s, SunJ, YanJ-q, LiuZ-k, LinS-h, LiuS-z Frank. Low-temperature and facile solution-processed two-dimensional TiS₂ as an effective electron transport layer for UV-stable planar perovskite solar cells [J]. Journal of Materials Chemistry A, 2018, 6(19): 9132-9138

[136] HuangP, YuanL-g, ZhangK-c, ChenQ-y, ZhouY, SongB, LiY-f. Room-temperature and aqueous solution-processed two-dimensional TiS₂ as an electron transport layer for highly efficient and stable planar n–i–p perovskite solar cells [J]. ACS Applied Materials & Interfaces, 2018, 10(17): 14796-14802

[137] ZhaoX-j, LiuS-s, ZhangH-t, ChangS-y, HuangW-c, ZhuB-w, ShenY, ShenC, WangD-y, YangY, WangM-k. 20% efficient perovskite solar cells with 2D electron transporting layer [J]. Advanced Functional Materials, 2019, 29(4): 1805168

[138] KimH S, LeeC R, ImJ H, LeeK B, MoehlT, MarchioroA, MoonS J, Humphry-BakerR, YumJ H, MoserJ E, GrätzelM, ParkN G. Lead iodide perovskite sensitized all-solid-state submicron thin film mesoscopic solar cell with efficiency exceeding 9% [J]. Scientific Reports, 2012, 2: 591

[139] JiangQ, ChuZ-m, WangP-y, YangX-l, LiuH, WangY, YinZ-g, WuJ-l, ZhangX-w, YouJ-b. Planar-structure perovskite solar cells with efficiency beyond 21% [J]. Advanced Materials, 2017, 29461703852

[140] HeoJ H, ImS H, NohJ H, MandalT N, LimC S, ChangJ A, LeeY H, KimH J, SarkarA, NazeeruddinM K, GrätzelM, SeokSII.. Efficient inorganic–organic hybrid heterojunction solar cells containing perovskite compound and polymeric hole conductors [J]. Nature Photonics, 2013, 76486-491

[141] WangZ-p, LinQ-q, WengerB, ChristoforoM G, LinY H, KlugM T, JohnstonM B, HerzL M, SnaithH J. High irradiance performance of metal halide perovskites for concentrator photovoltaics [J]. Nature Energy, 2018, 3(10): 855-861

[142] ShiH, LiuC-c, JiangQ-l, XuJ-k. Effective approaches to improve the electrical conductivity of PEDOT:PSS: A review [J]. Advanced Electronic Materials, 2015, 1(4): 1500017

[143] HwangJ, AmyF, KahnA. Spectroscopic study on sputtered PEDOT·PSS: Role of surface PSS layer [J]. Organic Electronics, 2006, 75387-396

[144] LiG, ZhuR, YangY. Polymer solar cells [J]. Nature Photonics, 2012, 6(3): 153-161

[145] YangJ-l, YanD-h, JonesT S. Molecular template growth and its applications in organic electronics and optoelectronics [J]. Chemical Reviews, 2015, 115(11): 5570-5603

[146] YangJ-l, YanD-h. Weak epitaxy growth of organic semiconductor thin films [J]. Chemical Society Reviews, 2009, 38(9): 2634

[147] WangC-h, LiY, ZhangC-j, ShiL-y, TongS-c, GuoB, ZhangJ, HeJ, GaoY-l, SuC-h, YangJ-l. Enhancing the performance of planar heterojunction perovskite solar cells using stable semiquinone and amine radical modified hole transport layer [J]. Journal of Power Sources, 2018, 390134-141

[148] HuangK-q, WangC-h, ZhangC-j, TongS-c, LiH-y, LiuB, GaoY-x, DongY-n, GaoY-l, PengY-y, YangJ-l. Efficient and stable planar heterojunction perovskite solar cells fabricated under ambient conditions with high humidity [J]. Organic Electronics, 2018, 55140-145

[149] HuangJ, WangC-h, LiuZ-y, QiuX-q, YangJ-l, ChangJ-j. Simultaneouly enhanced durability and performance by employing dopamine copolymerized PEDOT with high work function and water-proofness for inverted perovskite solar cells [J]. Journal of Materials Chemistry C, 2018, 6(9): 2311-2318

[150] WangC-h, ZhangC-j, TongS-c, ShenJ-q, WangC, LiY-z, XiaoS, HeJ, ZhangJ, GaoY-l, YangJ-l. Air-induced high-quality CH₃NH₃PbI₃ thin film for efficient planar heterojunction perovskite solar cells [J]. The Journal of Physical Chemistry C, 2017, 121(12): 6575-6580

[151] WangC-h, ZhangC-j, HuangY-l, TongS-c, WuH, ZhangJ, GaoY-l, YangJ-l. Degradation behavior of planar heterojunction CH₃NH₃PbI₃ perovskite solar cells [J]. Synthetic Metals, 2017, 227: 43-51

[152] WuR-s, YangJ-l, XiongJ, LiuP, ZhouC-h, HuangH, GaoY-l, YangB-c. Efficient electron-blocking layer-free planar heterojunction perovskite solar cells with a high open-circuit voltage [J]. Organic Electronics, 2015, 26: 265-272

[153] WuR-s, YangB-c, ZhangC-j, HuangY-l, CuiY-x, LiuP, ZhouC-h, HaoY-y, GaoY-l, YangJ-l. Prominent efficiency enhancement in perovskite solar cells employing silica-coated gold nanorods [J]. The Journal of Physical Chemistry C, 2016, 120(13): 6996-7004

[154] XiongJ, YangB-c, WuR-s, CaoC-h, HuangY-l, LiuC-b, HuZ-k, HuangH, GaoY-l, YangJ-l. Efficient and non-hysteresis CH₃NH₃PbI₃/PCBM planar heterojunction solar cells [J]. Organic Electronics, 2015, 24: 106-112

[155] LiuY, BagM, RennaL A, PageZ A, KimP, EmrickT, VenkataramanD, RussellT P. Understanding interface engineering for high-performance fullerene/perovskite planar heterojunction solar cells [J]. Advanced Energy Materials, 2016, 6(2): 1501606

[156] XiongJ, YangJ-l, YangB-c, ZhouC-h, HuX, XieH-p, HuangH, GaoY-l. Efficient and stable inverted polymer solar cells using TiO₂ nanoparticles and analysized by Mott-Schottky capacitance [J]. Organic Electronics, 2014, 1581745-1752

[157] XiongJ, YangB-c, YuanJ, FanL, HuX, XieH-p, LyuL, CuiR-l, ZouY-p, ZhouC-h, NiuD-m, GaoY-l, YangJ-l. Efficient organic photovoltaics using solution-processed, annealing-free TiO₂ nanocrystalline particles as an interface modification layer [J]. Organic Electronics, 2015, 17: 253-261

[158] XiongJ, YangB-c, ZhouC-h, YangJ-l, DuanH-c, HuangW-l, ZhangX, XiaX-d, ZhangL, HuangH, GaoY-l. Enhanced efficiency and stability of polymer solar cells with TiO₂ nanoparticles buffer layer [J]. Organic Electronics, 2014, 15(4): 835-843

[159] XiongJ, YangB-c, CaoC-h, WuR-s, HuangY-l, SunJ, ZhangJ, LiuC-b, TaoS-h, GaoY-l, YangJ-l. Interface degradation of perovskite solar cells and its modification using an annealing-free TiO₂ NPs layer [J]. Organic Electronics, 2016, 30: 30-35

[160] CaoC-h, ZhangC-j, YangJ-l, SunJ, PangS-p, WuH, WuR-s, GaoY-l, LiuC-b. Iodine and chlorine element evolution in CH₃NH₃PbI_3−xCl_x thin films for highly efficient planar heterojunction perovskite solar cells [J]. Chemistry of Materials, 2016, 28(8): 2742-2749

[161] LimK G, KimH B, JeongJ, KimH, KimJ Y, LeeT W. Boosting the power conversion efficiency of perovskite solar cells using self-organized polymeric hole extraction layers with high work function [J]. Advanced Materials, 2014, 26(37): 6461-6466

[162] ZuoC-t, DingL-m. Modified PEDOT layer makes a 1.52 V Voc for perovskite/PCBM solar cells [J]. Advanced Energy Materials, 2017, 7(2): 1601193

[163] LiuD-y, LiY, YuanJ-y, HongQ-m, ShiG-z, YuanD-x, WeiJ, HuangC-c, TangJ-x, FungM K. Improved performance of inverted planar perovskite solar cells with F4-TCNQ doped PEDOT:PSS hole transport layers [J]. Journal of Materials Chemistry A, 2017, 5125701-5708

[164] JiangK, WuF, ZhangG-y, Y. ChowP C, MaC, LiS-f, Sing WongK, ZhuL-n, YanH. Inverted planar perovskite solar cells based on CsI-doped PEDOT:PSS with efficiency beyond 20% and small energy loss [J]. Journal of Materials Chemistry A, 2019, 7(38): 21662-21667

[165] XiaY-j, SunK, ChangJ-j, OuyangJ-y. Effects of organic inorganic hybrid perovskite materials on the electronic properties and morphology of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and the photovoltaic performance of planar perovskite solar cells [J]. Journal of Materials Chemistry A, 2015, 3(31): 15897-15904

[166] MalinkiewiczO, YellaA, LeeY, HinM K, BolinkH J. Perovskite solar cells employing organic charge-transport layers [J]. Nature Photonics, 2014, 8(2): 128-132

[167] HöckerJ, KiermaschD, RiederP, TvingstedtK, BaumannA, DyakonovV. Efficient solution processed CH₃NH₃PbI₃ perovskite solar cells with polytpd hole transport layer [J]. Zeitschrift für Naturforschung A, 2019, 74(8): 665-672

[168] IntaniwetA, KeddieJ L, ShkunovM, SellinP J. High charge-carrier mobilities in blends of poly(triarylamine) and TIPS-pentacene leading to better performing X-ray sensors [J]. Organic Electronics, 2011, 12(11): 1903-1908

[169] LeemD S, WöbkenbergP, HuangJ-s, AnthopoulosT D, BradleyD D C, DemelloJ C. Micron-scale patterning of high conductivity poly(3,4-ethylendioxythiophene):poly(styrenesulfonate) for organic field-effect transistors [J]. Organic Electronics, 2010, 11(7): 1307-1312

[170] ZhengX-p, DengY-h, ChenB, WeiH-t, XiaoX, FangY-j, LinY-z, YuZ-h, LiuY, WangQ, HuangJ-s. Dual functions of crystallization control and defect passivation enabled by sulfonic zwitterions for stable and efficient perovskite solar cells [J]. Advanced Materials, 2018, 30(52): 1803428

[171] WangQ, BiC, HuangJ-s. Doped hole transport layer for efficiency enhancement in planar heterojunction organolead trihalide perovskite solar cells [J]. Nano Energy, 2015, 15: 275-280

[172] ShaoY-c, YuanY-b, HuangJ-s. Correlation of energy disorder and open-circuit voltage in hybrid perovskite solar cells [J]. Nature Energy, 2016, 1(1): 15001

[173] YouJ-b, MengL, SongT B, GuoT F, YangY M, ChangW H, HongZ-r, ChenH-j, ZhouH-p, ChenQ, LiuY-s, De MarcoN, YangY. Improved air stability of perovskite solar cells via solution-processed metal oxide transport layers [J]. Nature Nanotechnology, 2016, 11175-81

[174] ZuoC-t, DingL-m. Solution-processed Cu₂O and CuO as hole transport materials for efficient perovskite solar cells [J]. Small, 2015, 11(41): 5528-5532

[175] JengJ Y, ChenK C, ChiangT Y, LinP Y, TsaiT D, ChangY C, GuoT F, ChenP, WenT C, HsuY J. Nickel oxide electrode interlayer in CH₃NH₃PbI₃ perovskite/PCBM planar-heterojunction hybrid solar cells [J]. Advanced Materials, 2014, 26(24): 4107-4113

[176] ChenW, WuY-z, YueY-f, LiuJ, ZhangW-j, YangX-d, ChenH, BiE-b, AshrafulI, GrätzelM, HanL-y. Efficient and stable large-area perovskite solar cells with inorganic charge extraction layers [J]. Science, 2015, 350(6263): 944-948

[177] ChenW, ZhouY-c, WangL-j, WuY-h, TuB, YuB-b, LiuF-z, TamH W, WangG, DjurišIćA B, HuangL, HeZ-b. Molecule-doped nickel oxide: verified charge transfer and planar inverted mixed cation perovskite solar cell [J]. Advanced Materials, 2018, 30(20): 1800515

[178] ChowdhuryT H, AkhtaruzzamanM, KayeshM E, KanekoR, NodaT, LeeJ J, IslamA. Low temperature processed inverted planar perovskite solar cells by r-GO/CuSCN hole-transport bilayer with improved stability [J]. Solar Energy, 2018, 171652-657

[179] YeS-y, SunW-h, LiY-l, YanW-b, PengH-t, BianZ-q, LiuZ-w, HuangC-h. CuSCN-based inverted planar perovskite solar cell with an average pce of 15.6% [J]. Nano Letters, 2015, 15(6): 3723-3728

[180] YangD-b, SanoT, YaguchiY, SunH, SasabeH, KidoJ. Achieving 20% efficiency for low-temperature–processed inverted perovskite solar cells [J]. Advanced Functional Materials, 2019, 29(12): 1807556

[181] ChiangC H, TsengZ L, WuC G. Planar heterojunction perovskite/PC71BM solar cells with enhanced open-circuit voltage via a (2/1)-step spin-coating process [J]. Journal of Materials Chemistry A, 2014, 23815897-15903

[182] ChenC-c, HongZ-r, LiG, ChenQ, ZhouH-p, YangY. One-step, low-temperature deposited perovskite solar cell utilizing small molecule additive [J]. Journal of Photonics for Energy, 2015, 5(1): 057405

[183] GuerreroA, YouJ-b, ArandaC, KangY S, Garcia-BelmonteG, ZhouH-p, BisquertJ, YangY. Interfacial degradation of planar lead halide perovskite solar cells [J]. ACS Nano, 2016, 101218-224

[184] XiaF, WuQ-l, ZhouP-c, LiY, ChenX, LiuQ, ZhuJ, DaiS-y, LuY-l, YangS-f. Efficiency enhancement of inverted structure perovskite solar cells via oleamide doping of PCBM electron transport layer [J]. ACS Applied Materials & Interfaces, 2015, 7(24): 13659-13665

[185] KuangC-y, TangG, JiuT-g, YangH, LiuH-b, LiB-r, LuoW-n, LiX-d, ZhangW-j, LuF-s, FangJ-f, LiY-l. Highly efficient electron transport obtained by doping PCBM with graphdiyne in planar-heterojunction perovskite solar cells [J]. Nano Letters, 2015, 15(4): 2756-2762

[186] ChenK, HuQ, LiuT-h, ZhaoL-c, LuoD-y, WuJ, ZhangY-f, ZhangW, LiuF, RussellT P, ZhuR, GongQ-h. Charge-carrier balance for highly efficient inverted planar heterojunction perovskite solar cells [J]. Advanced Materials, 2016, 28(48): 10718-10724

[187] XieC-y, ZhouC-h, BinY, ShenL, KeL-l, DingL-m, YuanY-b. Silicon phthalocyanine passivation for fullerene-free perovskite solar cells with efficient electron extraction [J]. Applied Physics Express, 2019, 12(6): 064006

[188] ChenC, LiH-p, DingX-d, ChengM, LiH-n, XuL, QiaoF, LiH-m, SunL-c. Molecular engineering of triphenylamine-based non-fullerene electron-transport materials for efficient rigid and flexible perovskite solar cells [J]. ACS Applied Materials & Interfaces, 2018, 104538970-38977

[189] BailieC D, ChristoforoM G, MailoaJ P, BowringA R, UngerE L, NguyenW H, BurschkaJ, PelletN, LeeJ Z, GrätzelM, NoufiR, BuonassisiT, SalleoA, McgeheeM D. Semi-transparent perovskite solar cells for tandems with silicon and CIGS [J]. Energy & Environmental Science, 2015, 8(3): 956-963

[190] AhnJ, HwangH, JeongS, MoonJ. Metal-nanowire-electrode-based perovskite solar cells: Challenging issues and new opportunities [J]. Advanced Energy Materials, 2017, 7(15): 1602751

[191] ChenH-n, YangS-h. Carbon-based perovskite solar cells without hole transport materials: The front runner to the market? [J]. Advanced Materials, 2017, 29241603994

[192] DaiX-z, ZhangY, ShenH-p, LuoQ, ZhaoX-y, LiJ-b, LinH. Working from both sides: Composite metallic semitransparent top electrode for high performance perovskite solar cells [J]. ACS Applied Materials & Interfaces, 2016, 874523-4531

[193] LeeM, KoY, MinB K, JunY. Silver nanowire top electrodes in flexible perovskite solar cells using titanium metal as substrate [J]. ChemSusChem, 2016, 9(1): 31-35

[194] ZhangJ-h, LiF-s, YangK-y, VeeramalaiC P, GuoT-l. Low temperature processed planar heterojunction perovskite solar cells employing silver nanowires as top electrode [J]. Applied Surface Science, 2016, 369308-313

[195] HanK, XieM-l, ZhangL-p, YanL-p, WeiJ-f, JiG-q, LuoQ, LinJ, HaoY-y, MaC-q. Fully solution processed semi-transparent perovskite solar cells with spray-coated silver nanowires/ZnO composite top electrode [J]. Solar Energy Materials and Solar Cells, 2018, 185: 399-405

[196] XieM-l, LuH, ZhangL-p, WangJ, LuoQ, LinJ, BaL-x, LiuH, ShenW-z, ShiL-y, MaC-q. Fully solution–processed semi–transparent perovskite solar cells with ink–jet printed silver nanowires top electrode [J]. Solar RRL, 2018, 2(2): 1700184

[197] GranciniG, Roldán-CarmonaC, ZimmermannI, MosconiE, LeeX, MartineauD, NarbeyS, OswaldF, De AngelisF, GräetzelM, NazeeruddinM K. One-year stable perovskite solar cells by 2D/3D interface engineering [J]. Nature Communications, 2017, 811-8

[198] WangQ-f, ZhangW-h, ZhangZ-h, LiuS, WuJ-w, GuanY-j, MeiA-y, RongY-g, HuY, HanH-w. Crystallization control of ternary-cation perovskite absorber in triple-mesoscopic layer for efficient solar cells [J]. Advanced Energy Materials, 2020, 10(5): 1903092

[199] WeiZ-h, ChenH-n, YanK-y, YangS-h. Inkjet printing and instant chemical transformation of a CH₃NH₃PbI₃/nanocarbon electrode and interface for planar perovskite solar cells [J]. Angewandte Chemie International Edition, 2014, 534813239-13243

[200] ZhangF-g, YangX-c, WangH-x, ChengM, ZhaoJ-h, SunL-c. Structure engineering of hole–conductor free perovskite-based solar cells with low-temperature-processed commercial carbon paste as cathode [J]. ACS Applied Materials & Interfaces, 2014, 6(18): 16140-16146

[201] ZhouH-w, ShiY-t, DongQ-s, ZhangH, XingY-j, WangK, DuY, MaT-l. Hole-conductor-free, metal-electrode-free TiO₂/CH₃NH₃PbI₃ heterojunction solar cells based on a low-temperature carbon electrode [J]. The Journal of Physical Chemistry Letters, 2014, 5(18): 3241-3246

[202] ZhangC-x, LuoY-d, ChenX-h, ChenY-w, SunZ, HuangS-m. Effective improvement of the photovoltaic performance of carbon-based perovskite solar cells by additional solvents [J]. Nano-Micro Letters, 2016, 8(4): 347-357

[203] JinY, ChumanovG. Solution-processed planar perovskite solar cell without a hole transport layer [J]. ACS Applied Materials & Interfaces, 2015, 7(22): 12015-12021

[204] DengY-h, BrackleC H V, DaiX-z, ZhaoJ-j, ChenB, HuangJ-s. Tailoring solvent coordination for high-speed, room-temperature blading of perovskite photovoltaic films [J]. Science Advances, 2019, 5127537