Deying Luo

Abstract Obtaining micron-thick perovskite films of high quality is key to realizing efficient and stable positive (p)-intrinsic (i)-negative (n) perovskite solar cells1,2, but it remains a critical challenge. Here, we report an effective method for producing high-quality, micron-thick formamidinium-based perovskite films by forming coherent grain boundaries, where high-Miller-index-oriented grains grow on the low-Miller-index-oriented grains in a stabilized atmosphere.

Abstract Perovskite tandem solar cells show promising performance, but non-radiative recombination and its progressive worsening with time, especially in the mixed Sn–Pb low-bandgap layer, limit performance and stability. Here we find that mixed Sn–Pb perovskite thin films exhibit a compositional gradient, with an excess of Sn on the surface—and we show this gradient exacerbates oxidation and increases the recombination rate.