Abstract
Conventional titanium oxide (TiO2) as an electron transport layer (ETL) in hybrid organic-inorganic perovskite solar cells (PSCs) requires a sintering process at a high temperature to crystalize, which is not suitable for flexible PSCs and tandem solar cells with their low-temperature-processed bottom cell. Here, we introduce a low-temperature solution method to deposit a TiO2/tin oxide (SnO2) bilayer towards an efficient ETL. From the systematic measurements of optical and electronic properties, we demonstrate that the TiO2/SnO2 ETL has an enhanced charge extraction ability and a suppressed carrier recombination at the ETL/perovskite interface, both of which are beneficial to photo-generated carrier separation and transport. As a result, PSCs with TiO2/SnO2 bilayer ETLs present higher photovoltaic performance of the baseline cells compared with their TiO2 and SnO2 single-layer ETL counterparts. The champion PSC has a power conversion efficiency (PCE) of 19.11% with an open-circuit voltage (Voc) of 1.15 V, a short-circuit current density (Jsc) of 22.77 mA cm−2, and a fill factor (FF) of 72.38%. Additionally, due to the suitable band alignment of the TiO2/SnO2 ETL in the device, a high Voc of 1.18 V is achieved. It has been proven that the TiO2/SnO2 bilayer is a promising alternative ETL for high efficiency PSCs.
摘要
作为有机-无机钙钛矿杂化太阳能电池(PSCs)常用的电子传 输层(ETL), 氧化钛(TiO2)须在高温下烧结才能结晶, 因而难以适用 于柔性和串联叠层太阳能电池. 本文介绍了-种低温溶液法制备TiO2/氧化锡(SnO2)电子传输层, 并通过对TiO2/SnO2 ETL的系统光 学和电学性能测试, 证明TiO2/SnO2 ETL与钙钛矿层界面之间具有更好的电荷抽取能力和较少的载流子复合, 这有利于光致载流子 的分离和传输. 因此, 与单-的ETL相比, 基于TiO2/SnO2的PSCs展 现出更好的光伏性能, 其最大光电转换效率(PCE)为19.11%, 开路电压(Voc)为1.15 V, 短路电流密度为22.77 mA cm−2, 填充因子为72.38%. 此外, 由于TiO2/SnO2电子传输层与钙钛矿层能带更匹配, 电池的Voc 最高达到了1.18 V. 综上所述, 本文提出了-种具有广泛 应用前景的TiO2/SnO2电子传输层.
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References
Kojima A, Teshima K, Shirai Y, et al. Organometal halide perovskites as visible-light sensitizers for photovoltaic cells. J Am Chem Soc, 2009, 131: 6050–6051
Lee MM, Teuscher J, Miyasaka T, et al. Efficient hybrid solar cells based on meso-superstructured organometal halide perovskites. Science, 2012, 338: 643–647
Yang WS, Park BW, Jung EH, et al. Iodide management in formamidinium-lead-halide-based perovskite layers for efficient solar cells. Science, 2017, 356: 1376–1379
Jiang Q, Zhao Y, Zhang X, et al. Surface passivation of perovskite film for efficient solar cells. Nat Photon, 2019, 13: 460–466
Ma S, Cai M, Cheng T, et al. Two-dimensional organic-inorganic hybrid perovskite: from material properties to device applications. Sci China Mater, 2018, 61: 1257–1277
**ng G, Mathews N, Sun S, et al. Long-range balanced electron-and hole-transport lengths in organic-inorganic CH3NH3PbI3. Science, 2013, 342: 344–347
Liu Y, Yang Z, Cui D, et al. Two-inch-sized perovskite CH3NH3-PbX3 (X = Cl, Br, I) crystals: Growth and characterization. Adv Mater, 2015, 27: 5176–5183
Chen H, Ye F, Tang W, et al. A solvent- and vacuum-free route to large-area perovskite films for efficient solar modules. Nature, 2017, 550: 92–95
Manser JS, Kamat PV. Band filling with free charge carriers in organometal halide perovskites. Nat Photon, 2014, 8: 737–743
Mahmood K, Sarwar S, Mehran MT. Current status of electron transport layers in perovskite solar cells: materials and properties. RSC Adv, 2017, 7: 17044–17062
Calió L, Kazim S, Grätzel M, et al. Hole-transport materials for perovskite solar cells. Angew Chem Int Ed, 2016, 55: 14522–14545
Yang G, Tao H, Qin P, et al. Recent progress in electron transport layers for efficient perovskite solar cells. J Mater Chem A, 2016, 4: 3970–3990
Jiang C, Lim SL, Goh WP, et al. Improvement of CH3NH3PbI3 formation for efficient and better reproducible mesoscopic perovskite solar cells. ACS Appl Mater Interfaces, 2015, 7: 24726–24732
Rong Y, Hou X, Hu Y, et al. Synergy of ammonium chloride and moisture on perovskite crystallization for efficient printable mesoscopic solar cells. Nat Commun, 2017, 8: 14555
Jiang Q, Chu Z, Wang P, et al. Planar-structure perovskite solar cells with efficiency beyond 21%. Adv Mater, 2017, 29: 1703852
Liu M, Johnston MB, Snaith HJ. Efficient planar heterojunction perovskite solar cells by vapour deposition. Nature, 2013, 501: 395–398
Chen CW, Kang HW, Hsiao SY, et al. Efficient and uniform planar-type perovskite solar cells by simple sequential vacuum deposition. Adv Mater, 2014, 26: 6647–6652
Li Y, Cooper JK, Liu W, et al. Defective TiO2 with high photo-conductive gain for efficient and stable planar heterojunction perovskite solar cells. Nat Commun, 2016, 7: 12446
Shalan AE, Narra S, Oshikiri T, et al. Optimization of a compact layer of TiO2via atomic-layer deposition for high-performance perovskite solar cells. Sustain Energy Fuels, 2017, 1: 1533–1540
Conings B, Baeten L, Jacobs T, et al. An easy-to-fabricate low-temperature TiO2 electron collection layer for high efficiency planar heterojunction perovskite solar cells. APL Mater, 2014, 2: 081505
Liu Z, Chen Q, Hong Z, et al. Low-temperature TiOx compact layer for planar heterojunction perovskite solar cells. ACS Appl Mater Interfaces, 2016, 8: 11076–11083
Hu W, Zhou W, Lei X, et al. Low-temperature in situ amino functionalization of TiO2 nanoparticles sharpens electron management achieving over 21% efficient planar perovskite solar cells. Adv Mater, 2019, 31: 1806095
Liu X, Wu Z, Zhang Y, et al. Low temperature Zn-doped TiO2 as electron transport layer for 19% efficient planar perovskite solar cells. Appl Surf Sci, 2019, 471: 28–35
Unger EL, Hoke ET, Bailie CD, et al. Hysteresis and transient behavior in current-voltage measurements of hybrid-perovskite absorber solar cells. Energy Environ Sci, 2014, 7: 3690–3698
Chueh CC, Li CZ, Jen AKY. Recent progress and perspective in solution-processed interfacial materials for efficient and stable polymer and organometal perovskite solar cells. Energy Environ Sci, 2015, 8: 1160–1189
Wojciechowski K, Stranks SD, Abate A, et al. Heterojunction modification for highly efficient organic-inorganic perovskite solar cells. ACS Nano, 2014, 8: 12701–12709
Tan H, Jain A, Voznyy O, et al. Efficient and stable solution-processed planar perovskite solar cells via contact passivation. Science, 2017, 355: 722–726
Anaraki EH, Kermanpur A, Steier L, et al. Highly efficient and stable planar perovskite solar cells by solution-processed tin oxide. Energy Environ Sci, 2016, 9: 3128–3134
Jiang Q, Zhang L, Wang H, et al. Enhanced electron extraction using SnO2 for high-efficiency planar-structure HC(NH2)2PbI3-based perovskite solar cells. Nat Energy, 2017, 2: 16177
Jiang E, Yan J, Ai Y, et al. Defect engineering of oxygen vacancies in SnOx electron transporting layer for perovskite solar cells. Mater Today Energy, 2019, 12: 389–397
Song S, Kang G, Pyeon L, et al. Systematically optimized bilayered electron transport layer for highly efficient planar perovskite solar cells (η = 21.1%). ACS Energy Lett, 2017, 2: 2667–2673
Tavakoli MM, Yadav P, Tavakoli R, et al. Surface engineering of TiO2 ETL for highly efficient and hysteresis-less planar perovskite solar cell (21.4%) with enhanced open-circuit voltage and stability. Adv Energy Mater, 2018, 8: 1800794
Li Y, Meng L, Yang YM, et al. High-efficiency robust perovskite solar cells on ultrathin flexible substrates. Nat Commun, 2016, 7: 10214
Yang D, Zhou X, Yang R, et al. Surface optimization to eliminate hysteresis for record efficiency planar perovskite solar cells. Energy Environ Sci, 2016, 9: 3071–3078
Reyna Y, Salado M, Kazim S, et al. Performance and stability of mixed FAPbI3(0.85)MAPbBr3(0.15) halide perovskite solar cells under outdoor conditions and the effect of low light irradiation. Nano Energy, 2016, 30: 570–579
Correa Baena JP, Steier L, Tress W, et al. Highly efficient planar perovskite solar cells through band alignment engineering. Energy Environ Sci, 2015, 8: 2928–2934
Wang Q, Shao Y, Dong Q, et al. Large fill-factor bilayer iodine perovskite solar cells fabricated by a low-temperature solution-process. Energy Environ Sci, 2014, 7: 2359–2365
Wetzelaer GJAH, Scheepers M, Sempere AM, et al. Trap-assisted non-radiative recombination in organic-inorganic perovskite solar cells. Adv Mater, 2015, 27: 1837–1841
Huang X, Hu Z, Xu J, et al. Low-temperature processed SnO2 compact layer by incorporating TiO2 layer toward efficient planar heterojunction perovskite solar cells. Sol Energy Mater Sol Cells, 2017, 164: 87–92
Acknowledgements
This work was supported by the National Key Research and Development of China (2018YFB1500103 and 2018YFB0704100), the National Natural Science Foundation of China (61574145, 61874177, 51502315 and 61704176), Zhejiang Provincial Natural Science Foundation (LR16F040002), Zhejiang Energy Group (znkj-2018-118)).
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Ye J designed and engineered the experiments; Li N and Ai Y performed the experiments; Li N and Yan J conceived the fabrication process of the device; Li N and Jiang E performed the data analysis; Li N and Sheng J wrote the paper with the support from Yan B; Shou C and Lin L contributed to the theoretical analysis. All authors contributed to the general discussion.
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The authors declare that they have no conflict of interest.
Nan Li is a joint training MSc student in Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences (CAS), supervised by Prof. Jichun Ye. She received her BSc degree in new energy technology and engineering from Central South University, Changsha, China, in 2017. Her research interests focus on the interface engineering and carrier dynamic process for perovskite solar cells.
Jiang Sheng received his PhD degree in the Institute of Plasma Physics, Chinese Academy of Sciences, China, in 2012. After being a postdoctoral in NIMTE, CAS (2013–2015), he worked as an associate professor since then. His research mainly focuses on the nanomaterials, interface engineering and carrier dynamic process for perovskite solar cells, silicon heterojunction solar cells. He has published more than 40 peer-reviewed papers, and filed more than 10 patents.
Jichun Ye received PhD degree in materials science from the University of California, Davis, USA in 2005. He joined NIMTE, CAS, as a professor and PhD advisor since August of 2012. He was awarded for “Thousand Young Talents Program of China” in 2012. He has published more than 60 peer-reviewed papers with nearly 500 citations, and filed more than 40 patents (including 10 awarded patents).
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Li, N., Yan, J., Ai, Y. et al. A low-temperature TiO2/SnO2 electron transport layer for high-performance planar perovskite solar cells. Sci. China Mater. 63, 207–215 (2020). https://doi.org/10.1007/s40843-019-9586-x
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DOI: https://doi.org/10.1007/s40843-019-9586-x