能级精准调控的吡咯并二噻吩类免掺杂空穴传输材料设计及其高效钙钛矿太阳能电池研究

Organic-inorganic perovskite solar cells (PVSCs) are a class of photovoltaic technologies with great application potentials, wherein the hole transport layer (HTL) is an important device component. However, the organic HTL materials are confronted with several crucial issues such as high production cost, dependent performance on dopants and poor device stability. In this project, the molecular engineering of electron-donating fused dithieno[3,2-b:2',3'-d]pyrrole core that has been intensively studied in our group will be carried out by combing the theoretical calculations. Three aspects including the conjugated core extension, side arms number control and terminal oxygen-sulfur exchange of triphenylamine are proposed to fine tune the highest occupied molecular orbital levels of materials. Low-cost conjugated small molecules as HTL materials are thus developed with high hole mobility and matched energy levels with perovskite layers. By taking advantage of the device engineering, we will systematically investigate the performance of planar perovskite photovoltaic devices. Ultimately, dopant-free PVSCs with high photon-to-current conversion efficiency (PCE) over 21% are expected to be obtained. The correlations between material structures and the characteristic parameters of photovoltaic device will be analyzed. The hole exaction and transport processes that occur on the HTL/perovskite interfaces and in the HTL are also intensively studied. The intrinsic mechanisms of molecular engineering in improving the PCE of dopant-free PVSCs will be explored. This project can provide experimental references for the development of organic HTL materials and is of great significance for pushing forward the application of perovskite solar cells.

有机-无机钙钛矿太阳能电池是极具应用潜力的光伏技术，空穴传输层(HTL)是其器件的重要组成部分，但有机HTL材料面临着制备成本高、需掺杂及器件稳定性差等关键问题。本项目基于课题组深入研究的吡咯并二噻吩稠环给体核，结合理论计算开展三层次的分子工程(稠环共轭结构拓展、侧臂数目调节及三苯胺的端基氧-硫替换)，实现对材料最高占有分子轨道能级的精准调控。通过优化合成路线，开发低成本、与钙钛矿层能级匹配、高空穴迁移率的有机小分子HTL材料。系统考察其在平面正置结构器件中的光伏性能，结合器件工程，获取光电转化效率>21%的钙钛矿太阳能电池。分析材料结构与器件光伏特征参数的关系，深入研究HTL/钙钛矿层界面及HTL内部的空穴抽取与传输过程，探究分子工程提升免掺杂钙钛矿太阳能电池效率的内在机制。本项目为有机空穴传输层材料的开发提供实验参考，对于推动钙钛矿太阳能电池的应用推广具有重要意义。

空穴传输层是光伏器件的重要组成部分，但有机空穴传输材料（HTM）面临着制备成本高、需掺杂及器件稳定性差等关键问题。本项目基于课题组深入研究的吡咯并二噻吩（DTP）稠环给体核，结合理论计算开展了系统的分子工程。以噻吩单元分别为稠环共轭结构拓展和氮取代基，实现对材料最高占有分子轨道能级和空穴迁移率的精准调控，最终开发了系列线型有机空穴传输材料，并验证了其普适性。这类材料能够作为免掺杂HTM应用于钙钛矿光伏。进一步地，我们将这类材料成功应用于Sb2(S,Se)3太阳能电池，利用相邻噻吩单元与光吸收膜的Sb原子形成化学相互作用，成功实现了9.7%效率和高稳定性。从掺杂的本质出发，结合钙钛矿缺陷对光伏影响，提出了免掺杂空穴传输材料的设计原理与未来发展方向。本项目为有机空穴传输层材料的开发提供实验参考，对于推动先进太阳能电池的应用推广具有重要意义。