Chen Weijie

Three novel self-doped molecules named t-PyDIN, t-PyDINO and t-PyDINBr are developed as cathode interfacial materials for OSCs. The devices based on t-PyDINBr and t-PyDINO exhibit PCEs of 17.24 % and 17.56 %, respectively. Notably, the device based on t-PyDIN even reached a PCE of 18.25 %, which is improved by 51.3 % compared with that of the device without a cathode interfacial layer. This result is among the best efficiencies reported to date.

Abstract

Efficient cathode interfacial layers (CILs) are becoming essential elements for organic solar cells (OSCs). However, the absorption of commonly used cathode interfacial materials (CIMs) is either too weak or overlaps too much with that of photoactive materials, hindering their contribution to the light absorption. In this work, we demonstrate the construction of highly efficient CIMs based on 2,7-di-tert-butyl-4,5,9,10-pyrene diimide (t-PyDI) framework. By introducing amino, amino N-oxide and quaternary ammonium bromide as functional groups, three novel self-doped CIMs named t-PyDIN, t-PyDINO and t-PyDINBr are synthesized. These CIMs are capable of boosting the device performances by broadening the absorption, forming ohmic contact at the interface of active layer and electrode, as well as facilitating electron collection. Notably, the device based on t-PyDIN achieved a power conversion efficiency of 18.25 %, which is among the top efficiencies reported to date in binary OSCs.

Publication date: December 2022

Source: Journal of Energy Chemistry, Volume 75

Author(s): Siqing Nie, Qifan Feng, Ziheng Tang, Yaolin Hou, Xiaofeng Huang, Ruihao Chen, Fang Cao, Binghui Wu, Jun Yin, Jing Li, Nanfeng Zheng

Nature, Published online: 07 September 2022; doi:10.1038/s41586-022-05295-8

Publication date: January 2023

Source: Journal of Energy Chemistry, Volume 76

Author(s): Chunwei Wang, Zeyu Zhang, Zhuang Xiong, Xingyu Yue, Bo Zhang, Tingyuan Jia, Zhengzheng Liu, Juan Du, Yuxin Leng, Kuan Sun, Ruxin Li

An effective molecular engineering is demonstrated to simultaneously improve the performance and stability of perovskite devices. This strategy allows to obtain desired optoelectronic and chemical properties for novel nonspiro-based hole conductors, which leads to the fabrication of solar cells displaying remarkable efficiency of 21.2% with excellent stability under the harsh aging conditions.

Abstract

Despite considerable development in performance, both poor operational stability and high costs associated with hole conductors such as 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (spiro-OMeTAD) and Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA) of perovskite solar cells (PSCs) need to be addressed by the research community. Here, two nonspiro hole transporting materials (HTMs), namely HTM-1 and HTM-2, are designed and straightforwardly synthesized exhibiting remarkable electrochemical properties and hole mobilities. In particular, the PSC based on the methoxy derivative (HTM-2) exhibits a remarkable efficiency of 21.2% (stabilized efficiency of 20.8%), which is superior to the benchmark HTM spiro-OMeTAD (stabilized efficiency of 20.4%). These results establish that the molecular design is effective in improving the performance of PSCs. Importantly, these two HTMs show admissible long-term stability under different harsh conditions such as thermal stress up to 85 °C, high humidity level of 60% ± 10%, and continuous illumination over 1000 h. These insights allow correlating the impact of molecular design on optoelectronic properties of nonspiro-based hole conductors with the overall device performance.