Enhancing electron transport via graphene quantum dot/SnO 2 composites for efficient and durable flexible perovskite photovoltaics

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2019-01, Vol.7 (4), p.1878-1888
• Main Authors: Zhou, Yu, Yang, Sisi, Yin, Xuewen, Han, Jianhua, Tai, Meiqian, Zhao, Xingyue, Chen, Hui, Gu, Youchen, Wang, Ning, Lin, Hong
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/C8TA10168J

Recent advances in flexible perovskite solar cells (PSCs) have attracted considerable attention owing to their great potential for bendable and wearable electronic devices. In particular, developing high-quality low-temperature processed electron transport layers (ETLs) plays a pivotal role in realizing highly efficient flexible PSCs. Herein, we develop a facile strategy to fabricate graphene quantum dot/SnO 2 composites (G@SnO 2 ) as effective ETLs. Systematic optimization and investigation reveal that SnO 2 blended with graphene quantum dots with ca. 5 nm diameter (G5@SnO 2 ) has higher electron mobility, better film coverage and better energy level alignment compared to pristine SnO 2 , leading to promoted charge transfer and suppressed charge recombination. PSCs based on G5@SnO 2 demonstrate superior photovoltaic performance with a champion power conversion efficiency (PCE) of 19.6% and average PCE of 19.0%. Amazingly, the G5@SnO 2 based flexible PSCs obtain a best PCE and stabilized PCE of 17.7% and 17.2%, respectively, comparable to the highest PCEs recorded for flexible devices. Moreover, our flexible PSCs demonstrate outstanding mechanical durability, retaining over 91% of the initial PCE value after 500 bending cycles with a bending radius of 7 mm.