High-Performance Perovskite Photodetectors with Suppressed Dark Current Density via Small Molecule in Antisolvent Strategy.

Dark current density, a critical parameter in perovskite photodetectors (PPDs), largely depends on the quality of the perovskite film. Herein, we introduce a new small molecule in antisolvent strategy to enhance perovskite film quality during the crystallization of Cs(FAMA)Pb(IBr). COTIC-4Cl, an N-type narrow bandgap nonfullerene small molecule with specific functional group, could strongly bind to the uncoordinated Pb in the perovskite with assistance of antisolvent, enabling rapid supersaturation of perovskite solution and form dense structures under low-temperature annealing. This strategy leads to the decreased nonradiative recombination and improved carrier transport efficiency in COTIC-4Cl-modified perovskites. The PPDs based on COTIC-4Cl-modified films exhibit a broad spectral response from 300 to 815 nm, an exceptionally low dark current density of 2.17 × 10 A cm, and enhanced detectivities of 1.84 × 10and 3.09 × 10 Jones at 0 and -0.5 V bias, respectively. Improved responsivity and detectivity at 650-780 nm result from strong near-infrared light absorption by COTIC-4Cl. These optimized PPDs are comparable to commercial silicon photodetectors, promising significant advancements in cost-effective photodetector technology.