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 post-treatments, 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.

中文翻译：

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使用极性和非极性溶剂后处理对PEDOT：PSS进行处理，以有效地转化钙钛矿型太阳能电池

聚（3,4-乙撑二氧噻吩）：聚（苯乙烯磺酸盐）（PEDOT：PSS）已被广泛用作包括钙钛矿太阳能电池在内的许多光电器件中的空穴传导聚合物。但是，在常规的环境退火过程中，其电和表面性能不能得到很好的控制。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，不仅可以改变电导率和功函数，而且还可以重要地改变PEDOT：PSS薄膜的表面组成和形态。我们表明，在非极性甲苯蒸气环境中对PEDOT：PSS薄膜进行退火会导致电导率略有提高，并且功函数增加，同时保持表面成分和形态。CH ₃ NH ₃碘化铅_3个使用甲苯蒸气退火PEDOT钙钛矿太阳能电池：PSS空穴传输层（HTL的）产生在从与所述环境条件退火PEDOT的控制装置的功率转换效率（PCE）增加31.8％：PSS的HTL。由于减少了钙钛矿/ HTL界面处的陷阱状态，以及有效且平衡的电荷生成，传输和提取速率，所有光伏参数均得到了提高。相反，用极性EG溶剂洗涤PEDOT：PSS膜可去除表面上的PSS，增加表面粗糙度，并将电导率显着提高5个数量级，但功函数稍有降低。因此，CH ₃ NH ₃ PbI ₃钙洗净的PEDOT：PSS HTL的钙钛矿太阳能电池，由于钙钛矿/ HTL界面处陷阱状态的增加，导致控制装置的PCE降低了28.6％，这导致空穴提取效率低下。钙钛矿/ HTL界面处的电荷积累还反映了反向偏置区域中J – V曲线的严重滞后现象。这项工作强调了控制PEDOT：PSS HTL的电子和表面特性对于改善钙钛矿太阳能电池性能的重要性。