Organic hole transport materials (HTMs) are extensively studied in perovskite solar cells (PSCs). However, due to the inherently low charge carrier mobility, chemical dopants are often required to increase mobility and achieve high power conversion efficiency. Unfortunately, the use of dopants not only brings high costs, but also accelerates the degradation of perovskite, severely reducing the stability of perovskite solar cells. Therefore, developing efficient dopant-free HTMs has become a big challenge. Here, two linear molecules DTTTP-DPA and DTTTP-TPA were designed and synthesized, with diethyl 2,5-bis(thieno [3,2-b]thiophen-2-yl)terephthalate (DTTTP) as the core structure, methoxydiphenylamine/methoxytriphenylamine as the end group, respectively. Compared to diphenylamine, the triphenylamine end group endowed DTTTP-TPA with a longer conjugation length and a lower HOMO level. The longer conjugation is more conducive to charge transporting. While the lower HOMO level due to the weaker electron donating ability of triphenylamine, is potential to achieve a higher open-circuit voltage when used in PSCs. In addition, the carbonyl group in molecular structure could passivate the defect at perovskite/hole transport layer (HTL) interface. As a result, the dopant-free DTTTP-TPA device shows a high photovoltaic performance of 21.62%. At room temperature (30% relative humidity), the initial PCE of the unencapsulated device remains above 93% after 1000 h, showing excellent stability. Our work demonstrates that constructing linear type molecular structure with extended conjugation is an efficient way to enhance hole mobility and is promising to obtain dopant-free HTMs.

有机空穴传输材料（HTM）在钙钛矿太阳能电池（PSC）中得到广泛研究。然而，由于固有的低载流子迁移率，通常需要化学掺杂剂来提高迁移率并实现高载流子迁移率。电源转换效率。不幸的是，掺杂剂的使用不仅带来了高昂的成本，而且加速了钙钛矿的降解，严重降低了钙钛矿太阳能电池的稳定性。因此，开发高效的无掺杂HTM已成为一个巨大的挑战。在此，设计并合成了两种线性分子DTTTP-DPA和DTTTP-TPA，以2,5-双(噻吩并[3,2-b]噻吩-2-基)对苯二甲酸二乙酯(DTTTP)为核心结构，甲氧基二苯胺/甲氧基三苯胺分别作为端基。与二苯胺相比，三苯胺端基赋予DTTTP-TPA更长的共轭长度和更低的HOMO水平。共轭时间越长，越有利于电荷传输。而HOMO能级较低是由于三苯胺的给电子能力较弱，用于 PSC 时有可能实现更高的开路电压。此外，分子结构中的羰基可以钝化钙钛矿/空穴传输层（HTL）界面的缺陷。因此，无掺杂剂的 DTTTP-TPA 器件表现出高光伏业绩21.62%。在室温（30%相对湿度）下，未封装器件的初始PCE在1000小时后仍保持在93%以上，表现出优异的稳定性。我们的工作表明，构建具有扩展共轭的线性型分子结构是增强空穴迁移率的有效方法，并且有望获得无掺杂剂的 HTM。