Interfacial Voids Trigger Carbon-Based, All-Inorganic CsPbIBr ₂ Perovskite Solar Cells with Photovoltage Exceeding 1.33 V

Highlights

• A novel interface design of producing interfacial voids is proposed for CsPbIBr ₂ perovskite solar cells (PSCs), which is free of any extra modification layer.

• Interfacial voids improve absorption of CsPbIBr ₂ film, reduce saturation current density, and enlarge built-in potential of the PSCs.

• The PSC yields a superior efficiency of 10.20% with a record-high photovoltage of 1.338 V.

Electronic supplementary material

The online version of this article (10.1007/s40820-020-00425-1) contains supplementary material, which is available to authorized users.

Abstract

A novel interface design is proposed for carbon-based, all-inorganic CsPbIBr ₂ perovskite solar cells (PSCs) by introducing interfacial voids between TiO ₂ electron transport layer and CsPbIBr ₂ absorber. Compared with the general interfacial engineering strategies, this design exempts any extra modification layer in final PSC. More importantly, the interfacial voids produced by thermal decomposition of 2-phenylethylammonium iodide trigger three beneficial effects. First, they promote the light scattering in CsPbIBr ₂ film and thereby boost absorption ability of the resulting CsPbIBr ₂ PSCs. Second, they suppress recombination of charge carriers and thus reduce dark saturation current density ( J ₀) of the PSCs. Third, interfacial voids enlarge built-in potential ( V _bi) of the PSCs, awarding increased driving force for dissociating photo-generated charge carriers. Consequently, the PSC yields the optimized efficiency of 10.20% coupled with an open-circuit voltage ( V _oc) of 1.338 V. The V _oc achieved herein represents the best value among CsPbIBr ₂ PSCs reported earlier. Meanwhile, the non-encapsulated PSCs exhibit an excellent stability against light, thermal, and humidity stresses, since it remains ~ 97% or ~ 94% of its initial efficiency after being heated at 85 °C for 12 h or stored in ambient atmosphere with relative humidity of 30–40% for 60 days, respectively.

Electronic supplementary material

The online version of this article (10.1007/s40820-020-00425-1) contains supplementary material, which is available to authorized users.