Cu₂ZnSn(S,Se)₄ thin film solar cells fabricated with benign solvents

Abstract

Cu₂ZnSn(S,Se)₄ (CZTSSe) is considered as the promising absorbing layer materials for solar cells due to its earth-abundant constituents and excellent semiconductor properties. Through solution-processing, such as various printing methods, the fabrication of high performance CZTSSe solar cell could be applied to mass production with extremely low manufacturing cost and high yield speed. To better fulfill this goal, environmental-friendly inks/solutions are optimum for further reducing the capital investment on instrument, personnel and environmental safety. In this review, we summarized the recent development of CZTSSe thin films solar cells fabricated with benign solvents, such as water and ethanol. The disperse system can be classified to the true solution (consisting of molecules) and the colloidal suspension (consisting of nanoparticles).Three strategies for stabilization (i.e., physical method, chemical capping and self-stabilization) are proposed to prepare homogeneous and stable colloidal nanoinks. The one-pot self-stabilization method stands as an optimum route for preparing benign inks for its low impurity involvement and simple procedure. As-prepared CZTSSe inks would be deposited onto substrates to form thin films through spin-coating, spraying, electrodeposition or successive ionic layer adsorption and reaction (SILAR) method, followed by annealing in a chalcogen (S- or Se-containing) atmosphere to fabricate absorber. The efficiency of CZTSSe solar cell fabricated with benign solvents can also be enhanced by constituent adjustments, doping, surface treatments and blocking layers modifications, etc., and the deeper research will promise it a comparable performance to the non-benign CZTSSe systems.

Keywords

Cu₂ZnSn(S / Se)₄ (CZTSSe) / solar cell / benign solvents / metal chalcogenide complexes (MCCs) / solution processing

References

[1] Katagiri H, Jimbo K, Yamada S, Kamimura T, Maw W S, Fukano T, Ito T, Motohiro T. Enhanced conversion efficiencies of Cu₂ZnSnS₄-based thin film solar cells by using preferential etching technique. Applied Physics Express, 2008, 1(4): 041201

[2] Schubert B A, Marsen B, Cinque S, Unold T, Klenk R, Schorr S, Schock H W. Cu₂ZnSnS₄ thin film solar cells by fast coevaporation. Progress in Photovoltaics: Research and Applications, 2011, 19(1): 93–96

[3] Wang W, Winkler M T, Gunawan O, Gokmen T, Todorov T K, Zhu Y, Mitzi D B. Device characteristics of CZTSSe thin-film solar cells with 12.6% efficiency. Advanced Energy Materials, 2014, 4(7):

[4] Zhang H, Hu B, Sun L, Hovden R, Wise F W, Muller D A, Robinson R D. Surfactant ligand removal and rational fabrication of inorganically connected quantum dots. Nano Letters, 2011, 11(12): 5356–5361

[5] Kamoun N, Bouzouita H, Rezig B. Fabrication and characterization of Cu₂ZnSnS₄ thin films deposited by spray pyrolysis technique. Thin Solid Films, 2007, 515(15): 5949–5952

[6] Zeng X, Tai K F, Zhang T, Ho C W J, Chen X, Huan A, Sum T C, Wong L H. Cu₂ZnSn(S,Se)₄ kesterite solar cell with 5.1% efficiency using spray pyrolysis of aqueous precursor solution followed by selenization. Solar Energy Materials and Solar Cells, 2014, 124: 55–60

[7] Vigil-Galán O, Courel M, Espindola-Rodriguez M, Izquierdo-Roca V, Saucedo E, Fairbrother A. Toward a high Cu₂ZnSnS₄ solar cell efficiency processed by spray pyrolysis method. Journal of Renewable and Sustainable Energy, 2013, 5(5): 053137

[8] Yeh M Y, Lee C C, Wuu D S. Influences of synthesizing temperatures on the properties of Cu₂ZnSnS₄ prepared by sol-gel spin-coated deposition. Journal of Sol-Gel Science and Technology, 2009, 52(1): 65–68

[9] Jiang M, Lan F, Yan X, Li G. Cu₂ZnSn(S_1-xSe_x)₄thin film solar cells prepared by water-based solution process. Physica Status Solidi (RRL)- Rapid Research Letters, 2014, 8(3): 223–227

[10] Jiang M, Li Y, Dhakal R, Thapaliya P, Mastro M, Caldwell J, Kub F, Yan X. Cu₂ZnSnS₄ polycrystalline thin films with large densely packed grains prepared by sol-gel method. Journal of Photonics for Energy, 2011, 1(1): 019501

[11] Tian Q, Huang L, Zhao W, Yang Y, Wang G, Pan D. Metal sulfide precursor aqueous solutions for fabrication of Cu2ZnSn(S,Se)₄ thin film solar cells. Green Chemistry, 2015, 17(2): 1269–1275

[12] Kishore Kumar Y B, Suresh Babu G, Uday Bhaskar P, Sundara Raja V. Preparation and characterization of spray-deposited Cu₂ZnSnS₄ thin films. Solar Energy Materials and Solar Cells, 2009, 93(8): 1230–1237

[13] Zhong J, Xia Z, Zhang C, Li B, Liu X, Cheng Y B, Tang J. One-pot synthesis of self-stabilized aqueous nanoinks for Cu₂ZnSn(S,Se)₄ solar cells. Chemistry of Materials, 2014, 26(11): 3573–3578

[14] Woo K, Kim Y, Moon J. A non-toxic, solution-processed, earth abundant absorbing layer for thin-film solar cells. Energy & Environmental Science, 2012, 5(1): 5340–5345

[15] Larramona G, Bourdais S, Jacob A, Choné C, Muto T, Cuccaro Y, Delatouche B, Moisan C, Péré D, Dennler G. Efficient Cu₂ZnSnS₄ solar cells spray coated from a hydro-alcoholic colloid synthesized by instantaneous reaction. RSC Advances, 2014, 4(28): 14655–14662

[16] Larramona G, Bourdais S, Jacob A, Choné C, Muto T, Cuccaro Y, Delatouche B, Moisan C, Péré D, Dennler G. 8.6% efficient CZTSSe solar cells sprayed from water-ethanol CZTS colloidal solutions. Journal of Physical Chemistry Letters, 2014, 5(21): 3763–3767

[17] Li Z, Ho J C W, Lee K K, Zeng X, Zhang T, Wong L H, Lam Y M. Environmentally friendly solution route to kesterite Cu₂ZnSn(S,Se)₄ thin films for solar cell applications. RSC Advances, 2014, 4(51): 26888–26894

[18] Chen G, Yuan C, Liu J, Huang Z, Chen S, Liu W, Jiang G, Zhu C. Fabrication of Cu₂ZnSnS₄ thin films using oxides nanoparticles ink for solar cell. Journal of Power Sources, 2015, 276: 145–152

[19] van Embden J, Chesman A S, Della Gaspera E, Duffy N W, Watkins S E, Jasieniak J J. Cu₂ZnSnS_4xSe_4(1-x) solar cells from polar nanocrystal inks. Journal of the American Chemical Society, 2014, 136(14): 5237–5240

[20] Kang C C, Chen H F, Yu T C, Lin T C. Aqueous synthesis of wurtzite Cu₂ZnSnS₄ nanocrystals. Materials Letters, 2013, 96: 24–26

[21] Kush P, Ujjain S K, Mehra N C, Jha P, Sharma R K, Deka S. Development and properties of surfactant-free water-dispersible Cu₂ZnSnS₄ nanocrystals: a material for low-cost photovoltaics. Chemphyschem: a European journal of Chemical Physics and Physical Chemistry, 2013, 14(12): 2793–2799

[22] Liu W, Guo B, Mak C, Li A, Wu X, Zhang F. Facile synthesis of ultrafine Cu₂ZnSnS₄ nanocrystals by hydrothermal method for use in solar cells. Thin Solid Films, 2013, 535: 39–43

[23] Tian Q, Xu X, Han L, Tang M, Zou R, Chen Z, Yu M, Yang J, Hu J. Hydrophilic Cu₂ZnSnS₄ nanocrystals for printing flexible, low-cost and environmentally friendly solar cells. CrystEngComm, 2012, 14(11): 3847–3850

[24] Hsu K C, Liao J D, Chao L M, Fu Y S. Fabrication and characterization of Cu₂ZnSnS₄ powders by a hydrothermal method. Japanese Journal of Applied Physics, 2013, 52(6R): 061202

[25] Camara S M, Wang L, Zhang X. Easy hydrothermal preparation of Cu₂ZnSnS₄ (CZTS) nanoparticles for solar cell application. Nanotechnology, 2013, 24(49): 495401

[26] Jiang H, Dai P, Feng Z, Fan W, Zhan J. Phase selective synthesis of metastable orthorhombic Cu₂ZnSnS₄. Journal of Materials Chemistry, 2012, 22(15): 7502–7506

[27] Tiong V T, Bell J, Wang H. One-step synthesis of high quality kesterite Cu₂ZnSnS₄ nanocrystals- a hydrothermal approach. Beilstein Journal of Nanotechnology, 2014, 5: 438–446

[28] Tiong V T, Zhang Y, Bell J, Wang H. Phase-selective hydrothermal synthesis of Cu₂ZnSnS₄ nanocrystals: the effect of the sulphur precursor. CrystEngComm, 2014, 16(20): 4306–4313

[29] Zhao Y, Zhou W H, Jiao J, Zhou Z J, Wu S X. Aqueous synthesis and characterization of hydrophilic Cu₂ZnSnS₄ nanocrystals. Materials Letters, 2013, 96: 174–176

[30] Kovalenko M V, Scheele M, Talapin D V. Colloidal nanocrystals with molecular metal chalcogenide surface ligands. Science, 2009, 324(5933): 1417–1420

[31] Kovalenko M V, Bodnarchuk M I, Zaumseil J, Lee J S, Talapin D V. Expanding the chemical versatility of colloidal nanocrystals capped with molecular metal chalcogenide ligands. Journal of the American Chemical Society, 2010, 132(29): 10085–10092

[32] Jiang C, Lee J S, Talapin D V. Soluble precursors for CuInSe₂, CuIn_1-xGa_xSe₂, and Cu₂ZnSn(S,Se)₄ based on colloidal nanocrystals and molecular metal chalcogenide surface ligands. Journal of the American Chemical Society, 2012, 134(11): 5010–5013

[33] Zhou H, Duan H S, Yang W, Chen Q, Hsu C J, Hsu W C, Chen C C, Yang Y. Facile single-component precursor for Cu₂ZnSnS₄ with enhanced phase and composition controllability. Energy & Environmental Science, 2014, 7(3): 998–1005

[34] Su Z, Sun K, Han Z, Cui H, Liu F, Lai Y, Li J, Hao X, Liu Y, Green M A. Fabrication of Cu₂ZnSnS₄ solar cells with 5.1% efficiency via thermal decomposition and reaction using a non-toxic sol–gel route. Journal of Materials Chemistry. A, Materials for Energy and Sustainability, 2014, 2(2): 500–509

[35] Kim S, Kim J. Effect of selenization on sprayed Cu₂ZnSnS₄ thin film solar cell. Thin Solid Films, 2013, 547: 178–180

[36] Scragg J J, Berg D M, Dale P J A. 3.2% efficient Kesterite device from electrodeposited stacked elemental layers. Journal of Electroanalytical Chemistry, 2010, 646(1–2): 52–59

[37] Araki H, Kubo Y, Mikaduki A, Jimbo K, Maw W S, Katagiri H, Yamazaki M, Oishi K, Takeuchi A. Preparation of Cu₂ZnSnS₄ thin films by sulfurizing electroplated precursors. Solar Energy Materials and Solar Cells, 2009, 93(6–7): 996–999

[38] Scragg J J, Dale P J, Peter L M. Towards sustainable materials for solar energy conversion: preparation and photoelectrochemical characterization of Cu₂ZnSnS₄. Electrochemistry Communications, 2008, 10(4): 639–642

[39] Scragg J J, Dale P J, Peter L M. Synthesis and characterization of Cu₂ZnSnS₄ absorber layers by an electrodeposition-annealin88g route. Thin Solid Films, 2009, 517(7): 2481–2484

[40] Iljina J, Zhang R, Ganchev M, Raadik T, Volobujeva O, Altosaar M, Traksmaa R, Mellikov E. Formation of Cu₂ZnSnS₄ absorber layers for solar cells by electrodeposition-annealing route. Thin Solid Films, 2013, 537: 85–89

[41] Ennaoui A, Lux-Steiner M, Weber A, Abou-Ras D, Kötschau I, Schock H W, Schurr R, Hölzing A, Jost S, Hock R, Voß T, Schulze J, Kirbs A. Cu₂ZnSnS₄ thin film solar cells from electroplated precursors: Novel low-cost perspective. Thin Solid Films, 2009, 517(7): 2511–2514

[42] Wang Y, Ma J, Liu P, Chen Y, Li R, Gu J, Lu J, Yang S, Gao X. Cu₂ZnSnS₄ films deposited by a co-electrodeposition-annealing route. Materials Letters, 2012, 77: 13–16

[43] Pawar S M, Pawar B S, Moholkar A V, Choi D S, Yun J H, Moon J H, Kolekar S S, Kim J H. Single step electrosynthesis of Cu₂ZnSnS₄ (CZTS) thin films for solar cell application. Electrochimica Acta, 2010, 55(12): 4057–4061

[44] Schurr R, Hölzing A, Jost S, Hock R, Voß T, Schulze J, Kirbs A, Ennaoui A, Lux-Steiner M, Weber A, Kötschau I, Schock H W. The crystallisation of Cu₂ZnSnS₄ thin film solar cell absorbers from co-electroplated Cu-Zn-Sn precursors. Thin Solid Films, 2009, 517(7): 2465–2468

[45] Chan C P, Lam H, Surya C. Preparation of Cu₂ZnSnS₄ films by electrodeposition using ionic liquids. Solar Energy Materials and Solar Cells, 2010, 94(2): 207–211

[46] Mali S S, Patil B M, Betty C A, Bhosale P N, Oh Y W, Jadkar S R, Devan R S, Ma Y R, Patil P S. Novel synthesis of kesterite Cu₂ZnSnS₄ nanoflakes by successive ionic layer adsorption and reaction echnique: characterization and application. Electrochimica Acta, 2012, 66: 216–221

[47] Mali S S, Shinde P S, Betty C A, Bhosale P N, Oh Y W, Patil P S. Synthesis and characterization of Cu₂ZnSnS₄ thin films by SILAR method. Journal of Physics and Chemistry of Solids, 2012, 73(6): 735–740

[48] Shinde N M, Dubal D P, Dhawale D S, Lokhande C D, Kim J H, Moon J H. Room temperature novel chemical synthesis of Cu₂ZnSnS₄ (CZTS) absorbing layer for photovoltaic application. Materials Research Bulletin, 2012, 47(2): 302–307

[49] Shinde N M, Deshmukh P R, Patil S V, Lokhande C D. Aqueous chemical growth of Cu₂ZnSnS₄ (CZTS) thin films: air annealing and photoelectrochemical properties. Materials Research Bulletin, 2013, 48(5): 1760–1766

[50] Patel K, Shah D V, Kheraj V. Influence of deposition parameters and annealing on Cu₂ZnSnS₄ thin films grown by SILAR. Journal of Alloys and Compounds, 2015, 622: 942–947

[51] Su Z, Yan C, Sun K, Han Z, Liu F, Liu J, Lai Y, Li J, Liu Y. Preparation of Cu₂ZnSnS₄ thin films by sulfurizing stacked precursor thin films via successive ionic layer adsorption and reaction method. Applied Surface Science, 2012, 258(19): 7678–7682

[52] Gao C, Shen H, Jiang F, Guan H. Preparation of Cu₂ZnSnS₄ film by sulfurizing solution deposited precursors. Applied Surface Science, 2012, 261: 189–192

[53] Wangperawong A, King J S, Herron S M, Tran B P, Pangan-Okimoto K, Bent S F. Aqueous bath process for deposition of Cu₂ZnSnS₄ photovoltaic absorbers. Thin Solid Films, 2011, 519(8): 2488–2492

[54] Moriya K, Tanaka K, Uchiki H. Characterization of Cu₂ZnSnS₄thin films prepared by photo-chemical deposition. Japanese Journal of Applied Physics, 2005, 44(1B): 715–717

[55] Shinde N M, Lokhande C D, Kim J H, Moon J H. Low cost and large area novel chemical synthesis of Cu₂ZnSnS₄ (CZTS) thin films. Journal of Photochemistry and Photobiology A Chemistry, 2012, 235: 14–20

[56] Chen S, Walsh A, Gong X G, Wei S H. Classification of lattice defects in the kesterite Cu2ZnSnS₄ and Cu₂ZnSnSe₄ earth-abundant solar cell absorbers.  Advanced Materials,  2013,  25(11):  1522–1539

[57] Hergert F, Hock R. Predicted formation reactions for the solid-state syntheses of the semiconductor materials Cu₂SnX₃ and Cu₂ZnSnX₄ (X = S, Se) starting from binary chalcogenides. Thin Solid Films, 2007, 515(15): 5953–5956

[58] Shin S W, Pawar S M, Park C Y, Yun J H, Moon J H, Kim J H, Lee J Y. Studies on Cu₂ZnSnS₄ (CZTS) absorber layer using different stacking orders in precursor thin films. Solar Energy Materials and Solar Cells, 2011, 95(12): 3202–3206

[59] Mitzi D B, Gunawan O, Todorov T K, Wang K, Guha S. The path towards a high-performance solution-processed kesterite solar cell. Solar Energy Materials and Solar Cells, 2011, 95(6): 1421–1436

[60] Polizzotti A, Repins I L, Noufi R, Wei S H, Mitzi D B. The state and future prospects of kesterite photovoltaics. Energy & Environmental Science, 2013, 6(11): 3171–3182

[61] Vigil-Galán O, Courel M, Andrade-Arvizu J A, Sánchez Y, Espíndola-Rodríguez M, Saucedo E, Seuret-Jiménez D, Titsworth M. Route towards low cost-high efficiency second generation solar cells: current status and perspectives. Journal of Materials Science Materials in Electronics, 2015, 26(8): 5562–5573

[62] Chen S, Gong X G, Walsh A, Wei S H. Defect physics of the kesterite thin-film solar cell absorber Cu₂ZnSnS₄. Applied Physics Letters, 2010, 96(2): 021902

[63] Vigil-Galán O, Espíndola-Rodríguez M, Courel M, Fontané X, Sylla D, Izquierdo-Roca V, Fairbrother A, Saucedo E, Pérez-Rodríguez A. Secondary phases dependence on composition ratio in sprayed Cu₂ZnSnS₄ thin films and its impact on the high power conversion efficiency. Solar Energy Materials and Solar Cells, 2013, 117: 246–250

[64] Wen Q, Li Y, Yan J, Wang C. Crystal size-controlled growth of Cu₂ZnSnS₄ films by optimizing the Na doping concentration. Materials Letters, 2015, 140: 16–19

[65] Prabhakar T, Jampana N. Effect of sodium diffusion on the structural and electrical properties of Cu₂ZnSnS₄ thin films. Solar Energy Materials and Solar Cells, 2011, 95(3): 1001–1004

[66] Tong Z, Yan C, Su Z, Zeng F, Yang J, Li Y, Jiang L, Lai Y, Liu F. Effects of potassium doping on solution processed kesterite Cu₂ZnSnS₄ thin film solar cells. Applied Physics Letters, 2014, 105(22): 223903

[67] Johnson M, Baryshev S V, Thimsen E, Manno M, Zhang X, Veryovkin I V, Leighton C, Aydil E S. Alkali-metal-enhanced grain growth in Cu₂ZnSnS₄thin films. Energy & Environmental Science, 2014, 7(6): 1931–1938

[68] Zhou H, Song T B, Hsu W C, Luo S, Ye S, Duan H S, Hsu C J, Yang W, Yang Y. Rational defect passivation of Cu₂ZnSn(S,Se)₄ photovoltaics with solution-processed Cu₂ZnSnS₄:Na nanocrystals. Journal of the American Chemical Society, 2013, 135(43): 15998–16001

[69] Nagaoka A, Miyake H, Taniyama T, Kakimoto K, Nose Y, Scarpulla M A, Yoshino K. Effects of sodium on electrical properties in Cu₂ZnSnS₄ single crystal. Applied Physics Letters, 2014, 104(15): 152101

[70] Todorov T, Mitzi D B. Direct liquid coating of chalcopyrite light-absorbing layers for photovoltaic devices. European Journal of Inorganic Chemistry, 2010, 2010(1): 17–28

[71] Zhong J, Xia Z, Luo M, Zhao J, Chen J, Wang L, Liu X, Xue D J, Cheng Y B, Song H, Tang J. Sulfurization induced surface constitution and its correlation to the performance of solution-processed Cu₂ZnSn(S,Se)₄ solar cells. Scientific Reports, 2014, 4: 6288–6296

[72] Walter T, Herberholz R, Müller C, Schock H W. Determination of defect distributions from admittance measurements and application to Cu(In,Ga)Se₂ based heterojunctions. Journal of Applied Physics, 1996, 80(8): 4411

[73] Shin B, Bojarczuk N A, Guha S. On the kinetics of MoSe₂ interfacial layer formation in chalcogen-based thin film solar cells with a molybdenum back contact. Applied Physics Letters, 2013, 102(9): 091907

[74] Cui H, Lee C Y, Li W, Liu X, Wen X, Hao X. Improving efficiency of evaporated Cu₂ZnSnS₄ thin film solar cells by a thin Ag intermediate layer between absorber and back contact. International Journal of Photoenergy, 2015, 170507

[75] Liu X, Cui H, Li W, Song N, Liu F, Conibeer G, Hao X. Improving Cu₂ZnSnS₄ (CZTS) solar cell performance by an ultrathin ZnO intermediate layer between CZTS absorber and Mo back contact. Physica Status Solidi (RRL)- Rapid Research Letters, 2014, 8(12): 966–970

[76] Shin B, Gunawan O, Zhu Y, Bojarczuk N A, Chey S J, Guha S. Thin film solar cell with 8.4% power conversion efficiency using an earth-abundant Cu₂ZnSnS₄ absorber. Progress in Photovoltaics: Research and Applications, 2013, 21(1): 72–76

[77] Liu F, Sun K, Li W, Yan C, Cui H, Jiang L, Hao X, Green M A. Enhancing the Cu₂ZnSnS₄ solar cell efficiency by back contact modification: inserting a thin TiB₂ intermediate layer at Cu₂ZnSnS₄/Mo interface. Applied Physics Letters, 2014, 104(5): 051105

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (NSFC) (Grant Nos. 61274055 and 61322401), China Postdoctoral Science Foundation (No. 2013M542015) and Fundamental Research Funds for the Central Universities, Huazhong University of Science and Technology (No. CXY12M008). Jie Zhong acknowledges the support of Foundation for Scientific Research of Wuhan University of Technology.

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg