Bandgap Engineering through Halide Double-Perovskite Alloys: A High-Throughput First-Principles Study

Halide double perovskites are a new category of semiconductors that have shown promising optoelectronic properties. Their performance can be further improved by band engineering through alloying. Herein, based on the previous high-throughput first-principles study that predicts 118 thermodynamically stable halide double perovskites, 273 halide double-perovskite pairs with lattice mismatch less than 1% and bandgap difference larger than 0.5 eV are filtered. Low lattice mismatch favors high miscibility and coherent interfaces if made into heterostructures, and large-bandgap difference means wide tuning range. Further study on bandgap alignments shows that almost all halide double-perovskite pairs show type-I alignment, which favors high photoluminescence quantum yield (PLQY) if made into heterostructures. The study not only provides a list of candidate halide double-perovskite alloys for wide-range bandgap engineering and heterostructures with coherent interfaces, but also gives insights into developing new optoelectronic materials based on halide double perovskites and their alloys.