Hybrid-DFT study of halide perovskites, an energy-efficient material undercompressive pressure for piezoelectric applications.

Recent studies have reported that lead-halide perovskites are the most efficient energy-harvesting materials. Regardless of their high-output energy and structural stability, lead-based products have risk factors due to their toxicity. Therefore, lead-free perovskites that offer green energy are the expected alternatives. We have taken CsGeX 3 (X= Cl, Br, and I) as lead-free halide perovskites
despite knowing the low power conversion rate. Herein, we have tried to study the mechanisms of enhancement of energy-harvesting capabilities involving an interplay between structure and electronic properties. A density functional theory (DFT) simulation of these materials shows a decrease in the band gaps, lattice parameters, and volumes with increasing applied pressure. We report the
high piezoelectric responses and high electro-mechanical conversion rates, which are intriguing for generating electricity through mechanical stress.