Boosted charge extraction of NbO-enveloped SnO nanocrystals enables 24% efficient planar perovskite solar cells

• Published in: Energy & environmental science Vol. 14; no. 9; pp. 574 - 583
• Main Authors: Yuan, Ruihan, Cai, Bing, Lv, Yinhua, Gao, Xiang, Gu, Jinwen, Fan, Zhenghui, Liu, Xinhang, Yang, Chi, Liu, Mingzhen, Zhang, Wen-Hua
• Format: Journal Article
• Published: 15.09.2021
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/d1ee01519b

Planar perovskite solar cells (PSCs) have attracted extensive research attention owing to their simple architecture and manufacturing process. Improving the charge extraction ability of electron transport materials (ETMs) is imperative to enhance their power conversion efficiencies (PCEs). Herein, we report low-temperature solution-processed SnO 2 nanocrystals (SnO 2 NCs) enveloped by amorphous NbO x (SnO 2 /NbO x ) as efficient ETMs for planar PSCs, achieving an impressive PCE of 24.01% with negligible hysteresis, which is significantly superior to that of PSCs made from commercial SnO 2 (with PCEs up to 21.96%) and self-developed SnO 2 NCs (with PCEs up to 23.01%). The NbO x layer can simultaneously passivate defects at the ETMs/perovskite interface, promote charge extraction from perovskites, and improve the crystallinity of perovskite films. The unencapsulated PSC retains over 85% of its initial efficiency after 1000 h of light soaking (one sun), showing remarkable device stability. Furthermore, the low-temperature processed SnO 2 /NbO x ETMs are compatible with flexible substrates and present a maximum PCE of 20.00%. This work offers a facile approach to low-temperature processed ETMs with boosted carrier extraction ability, affording excellent device efficiency and stability for planar PSCs. A layer of amorphous NbO x is employed to envelope self-developed SnO 2 NCs and the resultant PSC achieves a PCE of 24.01% with negligible hysteresis and remarkable stability, which is among the most efficient planar PSCs.