Manipulation of PEDOT:PSS with Polar and Nonpolar Solvent Post-treatment for Efficient Inverted Perovskite Solar Cells
Manipulation of PEDOT:PSS with Polar and Nonpolar Solvent Post-treatment for Efficient Inverted Perovskite Solar Cells
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DOI：
10.1021/acsaem.0c01194
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发表时间：
2020-10-26
影响因子：
6.4
通讯作者：
Yu, Qiuming
中科院分区：
文献类型：
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作者：
Niu, Zhiyin;Zheng, Erjin;Yu, Qiuming
聚（3，4-乙撑二氧噻吩）：聚（苯乙烯磺酸盐）（PEDOT：PSS）作为空穴导电聚合物已广泛应用于包括钙钛矿太阳能电池在内的许多光电器件中。然而，在常规的环境退火期间，其电性能和表面性能不能很好地控制。在这里，我们应用溶剂后处理，包括甲苯蒸气退火和乙二醇（EG）洗涤，修改不仅导电性和功函数，但也重要的是，表面组成和形态的PEDOT：PSS薄膜。我们表明，退火PEDOT：PSS薄膜在非极性甲苯蒸气环境中的结果在一个稍微增强的电导率和增加的功函数，同时保持表面组成和形态。使用甲苯蒸气退火的PEDOT：PSS空穴传输层（HTL）的CH 3 NH3 PbI 3钙钛矿太阳能电池与具有环境条件退火的PEDOT：PSS HTL的对照器件相比产生31.8%的功率转换效率（PCE）增加。所有的光伏参数增加，因为减少陷阱状态在钙钛矿/HTL界面，以及有效和平衡的电荷产生，传输和提取率。相比之下，用极性EG溶剂洗涤PEDOT：PSS膜去除表面上的PSS，增加表面粗糙度，并且将电导率显著增加5个数量级，但略微降低功函数。因此，具有EG洗涤的PEDOT：PSS HTL的CH 3 NH3 PbI 3钙钛矿太阳能电池导致PCE比对照器件降低28.6%，因为钙钛矿/HTL界面处的陷阱态增加，这导致空穴提取效率低下。钙钛矿/HTL界面处的电荷积累也反映在反向偏压区的J-V曲线的严重滞后中。这项工作突出了控制PEDOT：PSS HTLs的电子和表面性质对于改善钙钛矿太阳能电池性能的重要性。
Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has been widely used as a hole-conducting polymer in many optoelectronic devices including perovskite solar cells. However, its electrical and surface properties are not well controlled during the conventional ambient annealing. Herein, we apply the solvent posttreatments, including toluene vapor annealing and ethylene glycol (EG) washing, to modify not only the electrical conductivity and work function but also, importantly, the surface composition and morphology of PEDOT:PSS thin films. We show that annealing PEDOT:PSS films in a nonpolar toluene vapor environment results in a slightly enhanced electrical conductivity and increased work function while maintaining the surface composition and morphology. The CH3NH3PbI3 perovskite solar cells using the toluene vapor-annealed PEDOT:PSS hole transporting layers (HTLs) yield a 31.8% increase in power conversion efficiency (PCE) from the control devices with the ambient condition-annealed PEDOT:PSS HTLs. All photovoltaic parameters are increased because of reduced trap states at the perovskite/HTL interface, as well as efficient and balanced charge generation, transport, and extraction rates. In contrast, washing PEDOT:PSS films with the polar EG solvent removes the PSS on the surface, increases the surface roughness, and dramatically increases the electrical conductivity by 5 orders of magnitude but slightly decreases the work function. Consequently, the CH3NH3PbI3 perovskite solar cells with EG-washed PEDOT:PSS HTLs result in a 28.6% decrease in PCE from the control devices because of the increased trap states at the perovskite/HTL interface, which leads to an inefficient hole extraction. The charge accumulation at the perovskite/HTL interface also reflects in a serious hysteresis of J-V curves in the reversed bias region. This work highlights the importance of controlling both electronic and surface properties of PEDOT:PSS HTLs for the improvement of perovskite solar cell performance.