Pressure‐Tuning Photothermal Synergy to Optimize the Photoelectronic Properties in Amorphous Halide Perovskite Cs(3)Bi(2)I(9)

Effective modification of the structure and properties of halide perovskites via the pressure engineering strategy has attracted enormous interest in the past decade. However, sufficient effort and insights regarding the potential properties and applications of the high‐pressure amorphous phase are still lacking. Here, the superior and tunable photoelectric properties that occur in the pressure‐induced amorphization process of the halide perovskite Cs(3)Bi(2)I(9) are demonstrated. With increasing pressure, the photocurrent with xenon lamp illumination exhibits a rapid increase and achieves an almost five orders of magnitude increment compared to its initial value. Impressively, a broadband photoresponse from 520 to 1650 nm with an optimal responsivity of 6.81 mA W(−1) and fast response times of 95/96 ms at 1650 nm is achieved upon successive compression. The high‐gain, fast, broadband, and dramatically enhanced photoresponse properties of Cs(3)Bi(2)I(9) are the result of comprehensive photoconductive and photothermoelectric mechanisms, which are associated with enhanced orbital coupling caused by an increase in Bi—I interactions in the [BiI(6)](3−) cluster, even in the amorphous state. These findings provide new insights for further exploring the potential properties and applications of amorphous perovskites.