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Light Processing Enables Efficient Carbon-Based, All-Inorganic Planar CsPbIBr2 Solar Cells with High Photovoltages
journal contribution
posted on 2018-12-31, 00:00 authored by Qianni Zhang, Weidong Zhu, Dazheng Chen, Zeyang Zhang, Zhenhua Lin, Jingjing Chang, Jincheng Zhang, Chunfu Zhang, Yue HaoInorganic
halide perovskite CsPbIBr2 possesses the most
balanced band gap and stability characters among all of the concerned
analogs for carbon-based, all-inorganic solar cells that are free
of any hole-transporting layers and noble-metal electrodes. Yet, the
current CsPbIBr2 solar cells seem to deliver the lowest
record efficiency. This is originally plagued by a serious energy
loss (Eloss) in the cells, which thus
limits their open-circuit voltages (Voc) severely. Herein, we demonstrate a light-processing technology
that can overcome this obstacle successfully, by enabling the full-coverage,
pure-phase CsPbIBr2 films featured with large grains, high
crystallinity, and preferential [100] grains orientation, along with
favorable electronic structure. It is achieved by the exposure of
CsPbIBr2 precursor film formed in a conventional one-step
spin-coating route to a simulated AM 1.5 G illumination before thermal
annealing. The resulting carbon-based, all-inorganic planar cells
give an optimized power conversion efficiency (PCE) of 8.60% with
the Voc of 1.283 V. Notably, such an impressive Voc stands the highest value among all of the
previously reported CsPbIBr2 solar cells; hence, its PCE
exceeds nearly all of them. Therefore, our work suggests a new route
to further improve the efficiency of low-cost, stable, and simple-fabrication
CsPbIBr2 solar cells.