Toward Broadband Imaging: Surface-Engineered PbS Quantum Dot/Perovskite Composite Integrated Ultrasensitive Photodetectors

PbS colloidal quantum dots passivated by the thiocyanate anion (SCN – ) are developed to combine with perovskite (CH 3 NH 3 PbI 3 ) as building blocks for UV–vis–NIR broadband photodetectors. Both high electrical conductivity and appropriate energy-level alignment are obtained by the in situ ligand exchange with SCN – . The PbS-SCN/CH 3 NH 3 PbI 3 composite photodetectors are sensitive to a broad wavelength range covering the UV–vis–NIR region (365–1550 nm), possessing an excellent responsivity of 255 A W –1 at 365 nm and 1.58 A W –1 at 940 nm, remarkably high detectivity of 4.9 × 10 13 Jones at 365 nm and 3.0 × 10 11 Jones at 940 nm, and fast response time of ≤42 ms. Furthermore, a 10 × 10 photodetector array is fabricated and integrated, which constitutes a high-performance broadband image sensor. Our approach paves a way for the development of highly sensitive broadband photodetectors/imagers that can be easily integrated.