Trans-interface engineering for reliable perovskite solar cells with reproducible stability

Abstract

High reproducibility in interface-dominated device stability is crucial for the industrialization of perovskite solar cells. Conventional interface engineering uses planar interlayers to passivate and interlock the perovskite and the charge-transport layer, which often involves a trade-off between efficient charge transport and high stability. In this work, we use trans-interface engineering to create vertically aligned, mechanically tough nanolinks that penetrate both the perovskite and the charge-transport layer, simultaneously enhancing interface reliability and charge transfer. Here, as a proof of concept, we pre-incorporated triple and single organic linkers into the perovskite and the charge-transport layer, respectively, and then applied azobisisobutyronitrile-derived cyanoisopropyl radicals to trigger polymerization of the two linkers within their respective layers and to vertically bond them at the heterointerfacial contacts. A perovskite/charge-transport-layer interface enhanced by trans-interface engineering shows superior mechanical reliability compared with other reported interfacial approaches. The resultant perovskite solar cells deliver improved power conversion efficiencies of up to 27.04% (certified at 26.67%). Under maximum-power-point tracking at one-sun-intensity illumination, 92% of the tested perovskite solar cells reached T80 lifetimes of 1,400 h, demonstrating improved stability and reproducibility. This high reliability stems largely from the trans-interface engineering-induced suppression of mechanical failure in device operation. This work points to a new direction for improving perovskite solar cells using trans-interfacial materials, which is also applicable to other multilayered optoelectronic devices beyond photovoltaics.