posted on 2021-04-20, 19:06authored byRohit
D. Chavan, Daniel Prochowicz, Bartłomiej Bończak, Marcin Fiałkowski, Mohammad Mahdi Tavakoli, Pankaj Yadav, Manushi J. Patel, Sanjeev K. Gupta, Pankaj N. Gajjar, Chang Kook Hong
Fullerene
derivatives with a strong electron-accepting ability
play a crucial role in enhancing both the performance and stability
of perovskite solar cells (PSCs). However, most of the used fullerene
molecules are based on [6,6]-phenyl-C61-butyric acid methyl
ester (PCBM), which limits the device performance due to difficulties
in preparing high-quality and uniform thin films. Herein, solution-processable
azahomofullerene (AHF) derivatives (abbreviated as AHF-1 and AHF-2)
are reported as novel and effective electron-transport layers (ETLs)
in p–i–n planar PSCs. Compared to the control PCBM ETL-based
PSCs, the devices based on AHFs exhibit higher photovoltaic performances,
which is attributed to the enhanced charge-transport properties and
improved layer morphology leading to a maximum power conversion efficiency
(PCE) of 20.21% in the case of the device based on AHF-2 ETL. Besides,
due to the preferable energy band alignment with the perovskite layer,
reduced trap states, and suppressed charge recombination, the device
with AHF-2 ETL exhibits significantly suppressed hysteresis and improved
stability under both ambient and thermal conditions.