Hysteresis-Free Lead-Free Double-Perovskite Solar Cells by Interface Engineering

TLDR

Hybrid perovskite solar cells are promising but rely on toxic lead; lead‑free double perovskites such as Cs₂AgBiBr₆ offer a nontoxic, stable alternative, yet device performance is still limited by hysteresis. The study demonstrates the first hysteresis‑free mesoporous Cs₂AgBiBr₆ solar cells with improved open‑circuit voltage. This was achieved by optimizing deposition conditions for a uniform Cs₂AgBiBr₆ layer and by selecting appropriate molecular or polymeric hole‑transport materials to engineer the device interfaces. The resulting devices show hysteresis‑free performance and higher open‑circuit voltage, marking a significant advance toward commercial viability of lead‑free perovskite solar cells.

Abstract

Hybrid perovskite solar cells have been creating considerable excitement in the photovoltaic community. However, they still rely on toxic elements, which impose severe limits on their commercialization. Lead-free double hybrid perovskites in the form of Cs2AgBiBr6 have been shown to be a promising nontoxic and highly stable alternative. Nevertheless, device development is still in its infancy, and performance is affected by severe hysteresis. Here we realize for the first time hysteresis-free mesoporous double-perovskite solar cells with no s-shape in the device characteristic and increased device open-circuit voltage. This has been realized by fine-tuning the material deposition parameters, enabling the growth of a highly uniform and compact Cs2AgBiBr6, and by engineering the device interfaces by screening different molecular and polymeric hole-transporting materials. Our work represents a crucial step forward in lead-free double perovskites with significant potential for closing the gap for their market uptake.