Tuning of the Interconnecting Layer for Monolithic Perovskite/Organic Tandem Solar Cells with Record Efficiency Exceeding 21%
Pang Wang, Wei Li, Oskar J. Sandberg, Chuanhang Guo, Rui Sun, Hui Wang, Donghui Li, Huijun Zhang, Shili Cheng, Dan Liu, Jie Min, Ardalan Armin, Tao Wang
Abstract
The photovoltaic performance of inorganic perovskite solar cells (PSCs) still lags behind the organic–inorganic hybrid PSCs due to limited light absorption of wide bandgap CsPbI3-xBrx under solar illumination. Constructing tandem devices with organic solar cells can effectively extend light absorption toward the long-wavelength region and reduce radiative photovoltage loss. Herein, we utilize wide-bandgap CsPbI2Br semiconductor and narrow-bandgap PM6:Y6-BO blend to fabricate perovskite/organic tandem solar cells with an efficiency of 21.1% and a very small tandem open-circuit voltage loss of 0.06 V. We demonstrate that the hole transport material of the interconnecting layers plays a critical role in determining efficiency, with polyTPD being superior to PBDB-T-Si and D18 due to its low parasitic absorption, sufficient hole mobility and quasi-Ohmic contact to suppress charge accumulation and voltage loss within the tandem device. These perovskite/organic tandem devices also display superior storage, thermal and ultraviolet stabilities.