物理化学学报 >> 2021, Vol. 37 >> Issue (4): 2004038.doi: 10.3866/PKU.WHXB202004038

所属专题： 金属卤化物钙钛矿光电材料和器件

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电泳法制备的致密氧化锡薄膜及其在高稳定性钙钛矿太阳能电池中的应用

宋沛泉, 谢立强(), 沈莉娜, 刘凯凯, 梁玉明, 林克斌, 卢建勋, 田成波, 魏展画()   

  • 收稿日期:2020-04-13 录用日期:2020-05-26 发布日期:2020-05-29
  • 通讯作者: 谢立强,魏展画 E-mail:lqxie@hqu.edu.cn;weizhanhua@hqu.edu.cn
  • 基金资助:
    国家自然科学基金(21805101);国家自然科学基金(51802102);国家自然科学基金(51902110);福建省自然科学基金(2019J01057);华侨大学中青年教师科技创新能力提升计划(ZQN-PY607);华侨大学科学基金(16BS201);华侨大学科学基金(17BS409);华侨大学科学基金(19BS105)

Stable Perovskite Solar Cells Using Compact Tin Oxide Layer Deposited through Electrophoresis

Peiquan Song, Liqiang Xie(), Lina Shen, Kaikai Liu, Yuming Liang, Kebin Lin, Jianxun Lu, Chengbo Tian, Zhanhua Wei()   

  • Received:2020-04-13 Accepted:2020-05-26 Published:2020-05-29
  • Contact: Liqiang Xie,Zhanhua Wei E-mail:lqxie@hqu.edu.cn;weizhanhua@hqu.edu.cn
  • About author:Email: weizhanhua@hqu.edu.cn (Z.W.)
    Email: lqxie@hqu.edu.cn (L.X.)
  • Supported by:
    the National Natural Science Foundation of China(21805101);the National Natural Science Foundation of China(51802102);the National Natural Science Foundation of China(51902110);the Natural Science Foundation of Fujian Province, China(2019J01057);the Promotion Program for Young and Middle-aged Teacher in Science and Technology Research of Huaqiao University, China(ZQN-PY607);the Scientific Research Funds of Huaqiao University, China(16BS201);the Scientific Research Funds of Huaqiao University, China(17BS409);the Scientific Research Funds of Huaqiao University, China(19BS105)

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摘要：

在平面型钙钛矿太阳能电池中常采用SnO2作为电子传输层材料，相应的SnO2薄膜常采用溶液旋涂法制备。但是由于前驱液中的纳米颗粒可能会发生部分团聚、基底和溶液难以完全避免灰尘等杂质颗粒混入，且最佳的SnO2电子传输层的厚度通常仅有约20 nm，所以这种方法制备的电子传输层难以保证严格致密和无纳米针孔。在本工作中，我们报道了一种电泳沉积制备致密SnO2薄膜的方法，并用其有效地提高了钙钛矿太阳能电池的光电转换效率和工况稳定性。通过电泳法，表面带负电荷的SnO2纳米颗粒在电场的作用下沉积到氧化铟锡(ITO)阳极表面，这种方法得到的薄膜比旋涂法制备的更为致密。将其应用于n-i-p结构的钙钛矿太阳能电池中，能够使得暗电流降低并抑制载流子的非辐射复合，从而提高电池的短路电流和开路电压，进而实现更高的光电转换效率(从18.17%提高到19.52%)，且能消除迟滞效应。更重要的是，长期工况稳定性测试表明基于电泳-旋涂法制备的器件在1个太阳的光照下、最大功率点处连续工作960 h后，仍然能够保持71%的初始效率；然而基于旋涂法制备的器件在工作100 h后即降低到初始效率的70%。本工作提供了一种全新的SnO2电子传输层的制备方法，显著地提高了器件性能和工况稳定性，后续有望应用于制备大面积器件和电池模组。

关键词: 电泳法, 氧化锡, 电子传输层, 钙钛矿太阳能电池

Abstract:

Tin oxide (SnO2) thin films are widely used as electron transport layers in planar perovskite solar cells (PSCs) and commonly prepared using solution-processed spin-coating. However, obtaining full coverage and pinhole-free surfaces for the spin-coated (SC) SnO2 is challenging because the nanocrystals in the precursor solution can undergo aggregation, wherein the precursor solution may contain dust particles, and the desired film thickness is rater small. Since dense electron transport layer films without pinholes are crucial in suppressing the non-radiative recombination of charge carriers in PSCs, developing deposition methods to prepare high-quality SnO2 films is important to improve the performance of planar PSCs. In this study, we investigated the application of electrophoresis (EP) in depositing compact and pinhole-free SnO2 thin films. We conducted electrophoresis to deposit a dense nanocrystalline film on the surface of Indium tin oxide (ITO) and employed a spin-coating step to adjust the thickness of the film and remove the residual SnO2 nanocrystalline precursor solution. This method was denoted as EP-SC. In the electrophoresis, the negatively charged SnO2 nanocrystals, caused by a strong electric field, migrated towards the surface of the ITO anode and formed more compactly packed thin films than that of the spin-coated SnO2. The atomic force microscopy (AFM) measurements demonstrated that the surface of EP-SC SnO2 was more uniform than that of SC SnO2 and there were no streaks and aggregated particles on the surface. This may have been due to the fact that the surface charge properties of the aggregated and dust particles in the precursor solution was different from that of the desired SnO2 nanocrystals. Hence, electrophoresis can selectively deposit SnO2 nanocrystals. Specifically, high-quality perovskites and electron transport layer interfaces can be achieved using this method. Both the electrochemical impedance spectroscopy (EIS) and dark J–V measurements showed that the PSCs using SnO2 prepared by electrophoresis followed by spin-coating demonstrated remarkably suppressed non-radiative recombination. As a result, the photoelectric power conversion efficiency increased from 18.17% (based on SC) to 19.52% (based on EP-SC) due to the enhanced short-circuit current and open-circuit voltage. The hysteresis of the device was eliminated. More importantly, the long-term stability measurements demonstrated that our device can maintain up to 71% of the initial efficiency after 960 h of continuous operation at the maximum power point (MPP) under one sun illumination. Whereas the device based on spin-coated SnO2 can maintain only up to 70% of the initial efficiency after working for 100 h. The results of this study can help in preparing electron transport layers to construct long-term stable planar PSCs, which are favorable for fabricating large-area PSCs and modules in future researches.

Key words: Electrophoresis, Tin oxide, Electron transport layer, Perovskite solar cell