Suppressing Leakage Currents and Improving Performance of Indoor Organic Photovoltaic Devices

Abstract

Organic photovoltaic(OPV)devices hold great promise for indoor light harvesting, offering a theoretical upper limit of power conversion efficiency that surpasses that of other photovoltaic technologies. However, the presence of high leakage currents in OPV devices commonly constrains their effective performance under indoor conditions. In this study, we identified that the origin of the high leakage currents in OPV devices lay in pinhole defects present within the active layer(AL). By integrating an automated spin-coating strategy with sequential deposition processes, we achieved the compactness of the AL and minimized the occurrence of pinhole defects therein.Experimental findings demonstrated that with an increase in the number of deposition cycles, the density of pinhole defects in the AL underwent a marked reduction.Consequently, the leakage current experienced a substantial decrease by several orders of magnitude which achieved through well-calibrated AL deposition procedures. This enabled a twofold enhancement in the power conversion efficiency(PCE)of the OPV devices under conditions of indoor illumination.

Keywords

organic photovoltaic(OPV) / indoor light harvesting / pinhole defect / leakage current / shunt resistance

References

[1] HEEGER A J. 25th anniversary article: bulk heterojunction solar cells: understanding the mechanism of operation[J]. Advanced Materials, 2014, 26(1): 10-27.

[2] SPANGGAARD H, KREBS F C. A brief history of the development of organic and polymeric photovoltaics[J]. Solar Energy Materials and Solar Cells, 2004, 83(2/3): 125-146.

[3] LIU Y H, LIU B W, MA C Q, et al. Recent progress in organic solar cells(Part I material science)[J]. Science China Chemistry, 2022, 65(2): 224-268.

[4] LIU Y H, LIU B W, MA C Q, et al. Recent progress in organic solar cells(Part II device engineering)[J]. Science China Chemistry, 2022, 65(8): 1457-1497.

[5] CHEN L X. Organic solar cells: recent progress and challenges[J]. ACS Energy Letters, 2019, 4(10): 2537-2539.

[6] SUN Y N, LIU T, KAN Y Y, et al. Flexible organic solar cells: progress and challenges[J]. Small Science, 2021, 1(5): 2100001.

[7] SUN L C, CHEN Y C, SUN M T, et al. Organic solar cells: physical principle and recent advances[J]. Chemistry, an Asian Journal, 2023, 18(5): e202300006.

[8] GUO Y Q, HUANG J, LI Z, et al. Design and synthesis of acceptor-donor-acceptor type nonfullerene acceptors using oxindole-based bridge for polymer solar cells applications[J]. Journal of Donghua University(English Edition), 2022, 39(3): 272-280.

[9] SHOCKLEY W, QUEISSER H J. Detailed balance limit of efficiency of p-n junction solar cells[J]. Journal of Applied Physics, 1961, 32(3): 510-519.

[10] HO J K W, YIN H, SO S K. From 33% to 57%: an elevated potential of efficiency limit for indoor photovoltaics[J]. Journal of Materials Chemistry A, 2020, 8(4): 1717-1723.

[11] CUI Y, WANG Y M, BERGQVIST J, et al. Wide-gap non-fullerene acceptor enabling highperformance organic photovoltaic cells for indoor applications[J]. Nature Energy, 2019, 4: 768-775.

[12] CUTTING C L, BAG M, VENKATARAMAN D. Indoor light recycling: a new home for organic photovoltaics[J]. Journal of Materials Chemistry C, 2016, 4(43): 10367-10370.

[13] JAHANDAR M, KIM S, LIM D C. Indoor organic photovoltaics for self-sustaining IoT devices: progress, challenges and practicalization[J]. ChemSusChem, 2021, 14(17): 3449-3474.

[14] XIE L, SONG W, GE J F, et al. Recent progress of organic photovoltaics for indoor energy harvesting[J]. Nano Energy, 2021, 82: 105770.

[15] LEE H K H, WU J Y, BARBÉ J, et al. Organic photovoltaic cells: promising indoor light harvesters for self-sustainable electronics[J]. Journal of Materials Chemistry A, 2018, 6(14): 5618-5626.

[16] LI B X, HOU B, AMARATUNGA G A J. Indoor photovoltaics, the next big trend in solution-processed solar cells[J]. InfoMat, 2021, 3(5): 445-459.

[17] CHEN Z H, YIN H, WEN Z C, et al. Organic indoor light harvesters achieving recorded output power over 500% enhancement under thermal radiated illuminances[J]. Science Bulletin, 2021, 66(16): 1641-1648.

[18] STEIM R, AMERI T, SCHILINSKY P, et al. Organic photovoltaics for low light applications[J]. Solar Energy Materials and Solar Cells, 2011, 95(12): 3256-3261.

[19] CUI Y, HONG L, HOU J H. Organic photovoltaic cells for indoor applications: opportunities and challenges[J]. ACS Applied Materials & Interfaces, 2020, 12(35): 38815-38828.

[20] RYU H S, PARK S Y, LEE T H, et al. Recent progress in indoor organic photovoltaics[J]. Nanoscale, 2020, 12(10): 5792-5804.

[21] DU B L, YANG R Z, HE Y Z, et al. Nondestructive inspection, testing and evaluation for Si-based, thin film and multi-junction solar cells: an overview[J]. Renewable and Sustainable Energy Reviews, 2017, 78: 1117-1151.

[22] LI M, ZHAO C, WANG Z K, et al. Interface modification by ionic liquid: a promising candidate for indoor light harvesting and stability improvement of planar perovskite solar cells[J]. Advanced Energy Materials, 2018, 8(24): 1801509.

[23] JAIN S C, KAPOOR A K, GEENS W, et al. Trap filled limit of conducting organic materials[J]. Journal of Applied Physics, 2002, 92(7): 3752-3754.

[24] SAEED M A, KIM S H, KIM H, et al. Indoor organic photovoltaics: optimal cell design principles with synergistic parasitic resistance and optical modulation effect[J]. Advanced Energy Materials, 2021, 11(27): 2003103.

[25] MORI S, GOTANDA T, NAKANO Y, et al. Investigation of the organic solar cell characteristics for indoor LED light applications[J]. Japanese Journal of Applied Physics, 2015, 54(7): 071602.

[26] JE H I, SHIN E Y, LEE K J, et al. Understanding the performance of organic photovoltaics under indoor and outdoor conditions: effects of chlorination of donor polymers[J]. ACS Applied Materials & Interfaces, 2020, 12(20): 23181-23189.

[27] YANG S S, HSIEH Z C, KESHTOV M L, et al. Toward high-performance polymer photovoltaic devices for low-power indoor applications[J]. Solar RRL, 2017, 1(12): 1700174.

[28] PARK S Y, LABANTI C, LUKE J, et al. Organic bilayer photovoltaics for efficient indoor light harvesting[J]. Advanced Energy Materials, 2022, 12(3): 2103237.

[29] ZHOU X B, WU H B, LIN B J, et al. Different morphology dependence for efficient indoor organic photovoltaics: the role of the leakage current and recombination losses[J]. ACS Applied Materials & Interfaces, 2021, 13(37): 44604-44614.

[30] ZHOU X B, WU H B, BOTHRA U, et al. Over 31% efficient indoor organic photovoltaicsenabled by simultaneously reduced trap-assisted recombination and non-radiative recombination voltage loss[J]. Materials Horizons, 2023, 10(2): 566-575.

[31] PROCTOR C M, NGUYEN T Q. Effect of leakage current and shunt resistance on the light intensity dependence of organic solar cells[J]. Applied Physics Letters, 2015, 106(8): 083301.

[32] MATHEWS I, KANTAREDDY S N, BUONASSISI T, et al. Technology and market perspective for indoor photovoltaic cells[J]. Joule, 2019, 3(6): 1415-1426.

[33] BURWELL G, SANDBERG O J, LI W, et al. Scaling considerations for organic photovoltaics for indoor applications[J]. Solar RRL, 2022, 6(7): 2200315.

[34] ZHANG M J, GUO X, MA W, et al. A largebandgap conjugated polymer for versatile photovoltaic applications with high performance[J]. Advanced Materials, 2015, 27(31): 4655-4660.

[35] YUAN J, ZHANG Y Q, ZHOU L Y, et al. Single-junction organic solar cell with over 15% efficiency using fused-ring acceptor with electrondeficient core[J]. Joule, 2019, 3(4): 1140-1151.

[36] TANG Z, ANDERSSON L M, GEORGE Z, et al. Interlayer for modified cathode in highly efficient inverted ITO-free organic solar cells[J]. Advanced Materials, 2012, 24(4): 554-558.

Funding

Fundamental Research Funds for the Central Universities, China(2232022A13)