Solar Energy, Vol.217, 93-104, 2021
Efficient strategies to improve the performance of 6,12-dihydroindeno [1,2-b]fluorine core based hole transport materials
For improving the performance of hole transport materials (HTM) in the utilization of perovskite solar cells (PSCs), the structure-performance relationships of HTM must be revealed. In this work, six HTMs with same 6,12dihydroindeno[1,2-b]fluorine (IDF) core are studied theoretically to reveal the influences of difference type and number of electron-donating group on the performances of HTMs. Results showed that star-shaped HTMs should have larger open-circuit voltage (VOC), better optical performances than linear-shaped HTMs. Meanwhile, using one thiophene substitute a benzene on the electron-donating group Diphenylamine derivative (DPA) is expected to enhance the VOC of PSCs and Stokes shift of HTM. Both the type and number of electron-donating group have slight effects on hole injection, electron-blocking and molecular stability of HTM. Most importantly, both thiophene substituted DPA (T-DPA) group and linear structure make the molecular stacking more compact, leading the transfer integral in the main hopping pathway improved evidently. Thus, the hole mobilities of HTMs are increased obviously. Furthermore, results also show that two thiophene substituted DPA could lead the molecular stacking more compact, which could be favorable for improving the hole mobility of HTMs. Our investigation proves and provides two efficient strategies to modulate the performances of HTMs and reveals the structure performance relationships of HTMs.
Keywords:Hole transport materials;Perovskite solar cells;Thiophene substituted DPA;Molecular crystal;Hole mobility