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 0.05 (FA 0.95 MA 0.05 ) 0.95 Pb(I 0.95 Br 0.05 ) 3 . COTIC-4Cl, an N-type narrow bandgap nonfullerene small molecule with specific functional group, could strongly bind to the uncoordinated Pb 2+ 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 –11 A cm –2, and enhanced detectivities of 1.84 × 10 14 and 3.09 × 10 12 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.