Gas-quenching is a promising technique for the up-scalable fabrication of metal halide perovskite solar cells (PSCs). However, it has been challenging to produce high-quality gas-quenched perovskite films without the use of the methylammonium (MA) cation. By employing tetramethylene sulfoxide (TMSO) as a ligand in the precursor solution, high-quality FA0.9Cs0.1PbI3 perovskite films have been successfully obtained by gas-quenching. A study on the precursor solution and film-forming process revealed the effect of TMSO on the formation of large-grain films, as well as the critical role of gas-quenching in regulating the intermediate films. The absolute MA-free perovskite device exhibits superior stability over the PSCs obtained with the MACl additive. The fabricated MA- and Br-free PSCs show a power conversion efficiency of 21.3% without any passivation treatment. Moreover, gas-quenching with TMSO enables a wide gas pressure processing window and superior accessibility to low-pressure processing, demonstrating its promising potential in up-scaling manufacturing of high-efficiency MA-free PSCs.
Yuting Lin,Jianyu Zhang,Wen-Jin Wang,Zhenguo Tang,Xianying Fang,Xu Xu,Fritz E. Kühn,Zheng Zhao,Qiang Yong,Ben Zhong Tang,Xu-Min Cai
The aggregation process plays a significant role in regulating the aggregate structures from molecules toward macroscopic photophysical properties. Pyrene (Py), as the simplest dimer candidate, serves as a suitable model for studying the aggregation. Herein, a series of Py-based aggregation-induced emission (AIE) materials have been investigated by clarifying the comprehensive roles of oxygen, substituents, molecular motion, and packing during aggregation, initially realizing the aim of controlling aggregate structures. With a largely planar and conjugated conformation, Py shows anomalous AIE characteristics due to the oxygen quenching at the molecular level but turn-on fluorescence in the aggregate state because of the oxygen isolation. Although introducing substituents induces molecular motion and similarly weakened luminescence in the molecular state, the impact of substituents on the aggregate-state photophysical properties enormously differs, exhibiting from weak blue, strong cyan, and strong green to weak yellow emissions, due to variable aggregate structures. Interestingly, the natural alicycle-substituted Py-dehydroabietylamine (Py-DAA) exhibits both mechanochromism and acidichromism, which can be synergistically applied in dynamic encryption-decryption. This work not only elucidates the unique AIE property of Py for the first time but also clarifies the bridging role of aggregation between single-molecular and aggregate states, achieving preliminary control over the aggregate structures.