Near-Infrared Organic-Inorganic Copper Halide Film with Spectral Response over 1400 nm for Photodetector Application

Organic-inorganic metal halides (OIMHs) have emerged as promising light absorbers for photodetector applications, especially Cu-based OIMHs. Herein, a novel Cu-based OIMH named (BA)₄Cu^II(Cu^IIn^III)_0.5Cl₈ has been synthesized by an ethanol assisted stirring method as powders, and a film sample has further been fabricated by a one step spin-coating method. (BA)₄Cu^II(Cu^IIn^III)_0.5Cl₈ exhibits a broadband absorption spectrum, peaking at 375, 620, as well as 875 nm, and a cutoff wavelength up to 1400 nm. In particular, a simple photoconductive photodetector based on the (BA)₄Cu^II(Cu^IIn^III)_0.5Cl₈ film as an absorber is first realized. The responsivity (R) and detectivity (D*) are as high as 2.6 × 10^-5 A/W and 7 × 10⁸ Jones at 980 nm, respectively. The measured linear dynamic range (LDR) is calculated to be 29 dB. Besides, a flexible photodetector with a polyvinyl chloride (PVC) substrate has been fabricated with a bending angle exceeding 90°, and the device can still work stably even after 80 bending cycles. This work provides a novel strategy to realize the high absorption of metal halides in the NIR region and highlights its potential in detection and imaging applications.