Tetraphenylbutadiene-Based Symmetric 3D Hole-Transporting Materials for Perovskite Solar Cells: A Trial Trade-off between Charge Mobility and Film Morphology

Two
three-dimensional symmetric tetraphenylbutadiene derivatives decorated
with diphenylamine or triphenylamine fragments are first prepared
for use as hole-transporting materials (HTMs) in perovskite solar
cells (PSCs). The HTMs are acquired using straightforward synthetic
methods and facile purification techniques. The thermal stability,
photophysical properties, electrochemical behaviors, computational
study, hole mobility, X-ray diffraction, hole transfer dynamics, hydrophobicity,
surface morphology, and photovoltaic performances of the HTMs are
discussed. The highest power conversion efficiency (PCE) of CJ-04-based cell is 13.75%, which is increased to 20.06% when CJ-03 is used as HTM, superior to the PCE of the cell based
on 2,2′,7,7′-tetrakis­(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene
(spiro-OMeTAD) (18.90%). The preparation cost of CJ-03 accounts for merely 23.1% of the price of commercial spiro-OMeTAD,
while the concentration of CJ-03 solution used in the
device fabrication (60.0 mg mL–1) is lower compared
with that of the spiro-OMeTAD solution (72.3 mg mL–1). These results corroborate that the screw-like HTMs with a highly
distorted configuration are facilely available and promising candidates
for PSCs. More importantly, a practical solution is proposed to achieve
moderate charge mobility and good film-formation ability of the HTMs
simultaneously.

首先，通过简便的合成方法和易于纯化的技术制备了装饰有二苯胺或三苯胺片段的三维对称四苯基丁二烯衍生物，作为钙钛矿太阳能电池（PSCs）中的空穴传输材料（HTMs）。这些HTMs的制备过程采用了直接合成手段及简便的纯化技术。本文详细讨论了HTMs的热稳定性、光物理性质、电化学行为、计算研究、空穴迁移率、X射线衍射、空穴转移动力学、疏水性和表面形貌，以及光伏性能。基于CJ-04的电池的最高功率转换效率（PCE）为13.75%，而当使用CJ-03作为HTM时，其PCE可提升至20.06%，超过了基于2,2′,7,7′-四（N,N-二-对-甲氧基苯基）胺-9,9′-螺双芴（spiro-OMeTAD）的电池的PCE（18.90%）。CJ-03的制备成本仅占商业spiro-OMeTAD价格的23.1%，而用于设备制备的CJ-03溶液浓度（60.0 mg mL–1）相较于spiro-OMeTAD溶液（72.3 mg mL–1）更低。这些结果证实了具有高度扭曲构型的螺旋状HTMs易于获得且是PSCs的有望候选材料。更重要的是，提出了一种实际可行的解决方案，以同时实现HTMs的适度电荷迁移率和良好的薄膜成膜能力。