Broad-Band Photodetectors Based on Copper Indium Diselenide Quantum Dots in a Methylammonium Lead Iodide Perovskite Matrix

Low-temperature solution-processed methylammonium lead iodide (MAPbI(3)) crystalline films have shown outstanding performance in optoelectronic devices. However, their high dark current and high noise equivalent power prevent their application in broad-band photodetectors. Here, we applied a facile solution-based antisolvent strategy to fabricate a hybrid structure of CuInSe2 quantum dots (CISe QDs) embedded into a MAPbI(3) matrix, which not only enhances the photodetector responsivity, showing a large on/off ratio of 10(4) at 2 V bias compared with the bare perovskite films, but also significantly (for over 7 days) improves the device stability, with hydrophobic ligands on the CuInSe2 QDs acting as a barrier against the uptake of environmental moisture. MAPbI(3)/CISe QD-based lateral photodetectors exhibit high responsivities of >0.5 A/W and 10.4 mA/W in the visible and near-infrared regions, respectively, partly because of the formation of a type II interface between the respective semiconductors but most significantly because of the efficient trap-state passivation of the perovskite grain surfaces, and the reduction in the twinning-induced trap density, which stems from both CISe QDs and their organic ligands. A large specific detectivity of 2.2 x 10(12) Jones at 525 nm illumination (1 mu W/cm(2)), a fast fall time of 236 mu s, and an extremely low noise equivalent power of 45 fW/Hz(1/2) have been achieved.