n-type absorber by Cd2+ doping achieves high-performance carbon-based CsPbIBr2 perovskite solar cells

High efficiency and stability have long been the key issues faced by perovskite solar cells (PSCs). It is found that the CsPbIBr2 all-inorganic perovskite has a suitable band gap and satisfactory stability, so it has attracted much attention. However, the many defects in the CsPbIBr2 film are one of the main prob-lems hindering the improvement of power conversion efficiency (PCE) of the CsPbIBr2 PSCs. The substi-tution of trace impurities is undoubtedly a simple, cost-effective and efficient strategy. In this work, an appropriate amount of Cd2+ (1.0% mol of Pb2+) is added into the CsPbIBr2 precursor solution to fabricate high quality CsPbIBr2 film with improved crystallinity, reduced trap density, suppressed photo-generated carrier recombination, displayed n-type doping and optimized energy level alignment. The corresponding carbon-based all-inorganic Cd2+-doped CsPbIBr2 PSCs achieve a maximum PCE of 10.63% with a high open circuit voltage (V-OC) of 1.324 V, which are much higher than those of the control one with a PCE of 8.48% and an V-OC of 1.235 V. The unencapsulated device can still retain more than 92% of the initial PCE when stored at ambient atmosphere (25 degrees C, relative humidity about 30%) for 40 days. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

The addition of an appropriate amount of Cd2+ into the CsPbIBr2 precursor solution can improve the film quality, enhance the efficiency of CsPbIBr2 PSCs, reduce trap density, suppress carrier recombination, exhibit n-type doping, and optimize energy level alignment, leading to higher PCE and improved stability.