Reduced Open-Circuit Voltage Loss of Perovskite Solar Cells via Forming p/p+ Homojunction and Interface Electric Field on the Surfaces of Perovskite Film

The severe nonradiative recombination losses limit the further improvement of open-circuit voltage (V-oc) and power conversion efficiency (PCE) of perovskite solar cells (PVSCs). In this work, the 4,4 '-cyclohexylidenebis [N,N-bis(4-methylphenyl) benzene amine] is dissolved into the antisolvent to prepare perovskite films, which reduces defects, improves the crystallinity, and induces a p/p(+) homojunction on the top surface of perovskite film. Besides, the 2-thiophenemethylammonium iodide and 2-thiophenethylammonium iodide form interface electric field and passivate defects on the bottom surface of perovskite film. The p/p(+) homojunction and interface electric field enhance the charges' separation and transportation efficiencies in the bulk perovskite film and at the perovskite/charge transport layer interfaces, which effectively reduces nonradiative recombination losses and V-oc loss of PVSCs. Consequently, low V-oc loss of 0.348 V is realized, resulting in the increase in V-oc from 1.082 to 1.172 V and PCE from19.15% to 23.44%. The optimized PVSCs without encapsulation maintain 88.23% of the original PCE after exposing in the air for 1500 h. This work provides a strategy to reduce the nonradiative recombination losses and V-oc loss by forming p/p(+) homojunction and interface electric field on the surfaces of perovskite film, which advances the development of high-performance PVSCs.

Automated summary

In this work, the formation of a p/p(+) homojunction and interface electric field on the surfaces of perovskite films is shown to reduce nonradiative recombination losses and V-oc loss, leading to improved performance of perovskite solar cells.