Effective bandgap narrowing and enhanced optoelectronic performance of Cs2PtBr6 double perovskites by pressure engineering

Tuning the structure–property relations of perovskites by pressure engineering holds great promise for discovering materials with favorable properties. The newly synthesized Cs 2 PtBr 6 double perovskite exhibits excellent water resistance and chemical stability. Yet its photoelectric conversion efficiency is limited by its intrinsic wide-bandgap nature. In this work, based on density functional theory calculations, we demonstrate the bandgap narrowing of Cs 2 PtBr 6 via pressure engineering and maintain its structural stability. Strikingly, upon applying pressure up to 12 GPa, the bandgap value decreases to 1.34 eV, which exactly reaches the optimal bandgap required by the Shockley–Queisser efficiency limit. Moreover, optical calculation analysis shows that the optical absorption of Cs 2 PtBr 6 exhibits a significant improvement within the visible range. Therefore, the potential of Cs 2 PtBr 6 as a photovoltaic material by pressure engineering is improved. This work is useful for designing and synthesizing new perovskite materials with enhanced performance.