Facile star-shaped tetraphenylethylene-based molecules with fused ring-terminated diarylamine as interfacial hole transporting materials for inverted perovskite solar cells

• Published in: Materials chemistry frontiers 2021-02, Vol.5 (3), p.1373-1387
• Main Authors: Chen, Yung-Chung, Lin, Ding-Zhi, Wang, Jhong-Ci, Ni, Jen-Shyang, Yu, Yang-Yen, Chen, Chih-Ping
• Format: Article
• Language: English
• Subjects: Benzene; Charge transfer; Energy conversion efficiency; Hydrophobicity; Morphology; Naphthalene; Perovskites; Photovoltaic cells; Solar cells
• ISSN: 2052-1537; 2052-1537
• DOI: 10.1039/d0qm00728e

In this work, three p-type small molecules ( CL-1-3 ) based on tetraphenylethylene as the core and fused ring-terminated diarylamine as electron donating groups were synthesized. The design strategy for fused ring-terminated diarylamines involved the use of benzene for CL-1 , naphthalene for CL-2 , and pyrene for CL-3 . We then investigated the effects of various electron-donating groups on their electronic properties. Among them, the CL-3 sample showed the highest T g value (192 °C) and 5 wt% decomposition temperature (473 °C). In the presence of urea as an additive, inverted perovskite solar cells (PSCs) employing inorganic/organic (NiOx/ CL series) bilayer HTLs and reference inorganic (NiOx)-only HTL were fabricated. Notably, the NiOx/ CL-3 -based cell exhibited the champion power conversion efficiency of 20.15%, which outperformed the NiOx-only cell (PCE = 18.66%) due to its smoother surface morphology, better interface charge transfer and matched energy-level alignment. Furthermore, this device also exhibited greater hydrophobicity and acceptable long-term stability. This work presents a new molecular design and in-depth understanding of the bilayer HTL strategy and its potential for the development of highly efficient cell performances. Three p-type small molecules ( CL-1-3 ) based on tetraphenylethylene as the core and different π-conjugation diarylamines as linkers are synthesized. The bilayer HTL of the NiOx/ CL-3 -based cell exhibits the best power conversion efficiency of 20.15%.