Near-Infrared Organic–Inorganic\nCopper Halide\nFilm with Spectral Response over 1400 nm for Photodetector Application

Organic–inorganic metal halides (OIMHs) have emerged\nas\npromising light absorbers for photodetector applications, especially\nCu-based OIMHs. Herein, a novel Cu-based OIMH named (BA)<sub>4</sub>Cu<sup>II</sup>(Cu<sup>I</sup>In<sup>III</sup>)<sub>0.5</sub>Cl<sub>8</sub> has been synthesized by an ethanol assisted stirring method\nas powders, and a film sample has further been fabricated by a one\nstep spin-coating method. (BA)<sub>4</sub>Cu<sup>II</sup>(Cu<sup>I</sup>In<sup>III</sup>)<sub>0.5</sub>Cl<sub>8</sub> exhibits a broadband\nabsorption spectrum, peaking at 375, 620, as well as 875 nm, and a\ncutoff wavelength up to 1400 nm. In particular, a simple photoconductive\nphotodetector based on the (BA)<sub>4</sub>Cu<sup>II</sup>(Cu<sup>I</sup>In<sup>III</sup>)<sub>0.5</sub>Cl<sub>8</sub> film as an absorber\nis first realized. The responsivity (<i>R</i>) and detectivity\n(<i>D</i>*) are as high as 2.6 × 10<sup>–5</sup> A/W and 7 × 10<sup>8</sup> Jones at 980 nm, respectively. The\nmeasured linear dynamic range (LDR) is calculated to be 29 dB. Besides,\na flexible photodetector with a polyvinyl chloride (PVC) substrate\nhas been fabricated with a bending angle exceeding 90°, and the\ndevice can still work stably even after 80 bending cycles. This work\nprovides a novel strategy to realize the high absorption of metal\nhalides in the NIR region and highlights its potential in detection\nand imaging applications.