Hole transport layers (HTLs) play a significant role in the performance of perovskite solar cells. A new class of linear small-molecules based on bis(4-methylthio)phenyl)amine as an end group, carbon, oxygen and sulfur as the center atoms for the center unit (denoted as MT-based small-molecule), respectively, have been applied as HTL, and two of them presented the efficiency over 20% in the planar inverted perovskite solar cells (PSCs), which demonstrated a significant improvement in comparison with the widely used HTL, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (known as PEDOT:PSS), in the planar inverted architecture. The ultrafast carrier dynamics show that the excited hot carrier cooling process of MT-based small-molecule HTL samples is faster than that of PEDOTPSS samples. The kinetic analysis of photo-bleaching peaks of femtosecond transient absorption spectra reveals that the traps at the interface between MT-based small-molecule HTLs and MAPbI₃ can be filled much quicker than that at PEDOT/MAPbI₃ interfaces. Moreover, the hole injection time from MAPbI₃ to MT-based small-molecule HTLs is around 10 times quicker than that to PEDOTPSS. Such quick trap filling and hole extraction bring a significant enhancement in photovoltaic performances. These findings uncover the carrier transport mechanisms and illuminate a promising approach for the design of new HTLs for highly-efficient perovskite solar cells.

空穴传输层（HTL）在钙钛矿太阳能电池的性能中起重要作用。以双（4-甲硫基）苯基）胺为末端基团，碳，氧和硫为中心单元的中心原子的新型线性小分子（分别表示为MT基小分子），已被用作HTL，其中两个在平面倒钙钛矿太阳能电池（PSC）中的效率超过20％，与广泛使用的HTL聚（3,4-乙撑二氧噻吩）： （苯乙烯磺酸盐）（称为PEDOT：PSS），在平面倒置结构中。超快载流子动力学表明，基于MT的小分子HTL样品的激发热载流子冷却过程比PEDOTPSS样品快。_3的填充速度比PEDOT / MAPbI ₃界面快得多。而且，从MAPbI ₃到基于MT的小分子HTL的空穴注入时间比对PEDOTPSS的注入时间快10倍左右。这样的快速阱填充和空穴提取带来了光伏性能的显着提高。这些发现揭示了载流子传输机制，并为高效率钙钛矿太阳能电池的新型HTL设计提供了一种有前途的方法。