Expanding the Absorption of Double Perovskite Cs2AgBiBr6 to NIR Region

The toxicity of lead-based halide perovskites hampersbroad applicationin optoelectronics. The lead-free perovskite Cs2AgBiBr6 is considered a promising candidate, owing to its long carrierlifetime and outstanding stability. However, the relatively largebandgap hinders its absorption in the visible region and thus theapplication of its photoelectric properties in the visible and near-infrared(NIR) regions. Therefore, the expansion of absorption to the longerwavelengths, even the NIR region, makes sense for solar cells andphotodetector applications. Facile elemental doping or substitutionof Cs2AgBiBr6 makes it potentially desirablefor applications in both visible and NIR regions. As a result, band-edgeadjustment to expand the absorption onset or trace deep-energy-leveldoping with a new intermediate band was achieved. Here, we summarizethe elemental doping results and review the potential applicationof Cs2AgBiBr6 from these two aspects and giveconstructive perspectives for further development of lead-free perovskite.