Ultrasensitive solution-processed broad-band photodetectors using CH3NH3PbI3 perovskite hybrids and PbS quantum dots as light harvesters

Abstract

Sensing from ultraviolet-visible to infrared is critical for both scientific and industrial applications. In this work, we demonstrate solution-processed ultrasensitive broad-band photodetectors (PDs) utilizing organolead halide perovskite materials (CH₃NH₃PbI₃) and PbS quantum dots (QDs) as light harvesters. Through passivating the structural defects on the surface of PbS QDs with diminutive molecular-scaled CH₃NH₃PbI₃, both trap states in the bandgap of PbS QDs for charge carrier recombination and the leakage currents occurring at the defect sites are significantly reduced. In addition, CH₃NH₃PbI₃ itself is an excellent light harvester in photovoltaics, which contributes a great photoresponse in the ultraviolet-visible region. Consequently, operated at room temperature, the resultant PDs show a spectral response from 375 nm to 1100 nm, with high responsivities over 300 mA W⁻¹ and 130 mA W⁻¹, high detectivities exceeding 10¹³ Jones (1 Jones = 1 cm Hz^1/2 W⁻¹) and 5 × 10¹² Jones in the visible and near infrared regions, respectively. These device performance parameters are comparable to those from pristine inorganic counterparts. Thus, our results offer a facile and promising route for advancing the performance of broad-band PDs.