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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 Cs0.05(FA0.95MA0.05)0.95Pb(I0.95Br0.05)3. COTIC-4Cl, an N-type narrow bandgap nonfullerene small molecule with specific functional group, could strongly bind to the uncoordinated Pb2+ 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 × 1014and 3.09 × 1012 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.
Xie et al. (Tue,) studied this question.