Self-powered, ultrabroad band photodetectors with large open circuit voltage using colloidal PbSe QDs

Broad band photodetectors are found to be the inevitable component both in scientific and industrial fields. Here, PbSe colloidal QDs prepared by a simple, inexpensive hot injection method were used to fabricate ultra-broadband photodetectors with visible to near-infrared sensing capabilities. The as-fabricated photodetector has a wide spectral response and a stable photoelectric response to lasers with wavelengths ranging from 405 nm to 1550 nm. The responsivity of the photovoltaic detector is 1.43 mA W^-1 at 405 nm, 4.67 mA W^-1 at 980 nm and 0.2 mA W^-1 at 1550 nm. The device with the optimized structure provides the maximum <i>V</i> _oc of 250 mV under 780 nm light illumination and 100 mV even under 1550 nm illumination. Specifically, the detectivity value reaches up to 4.54 × 10⁹ Jones under 1550 nm laser illumination with an intensity of 0.41 mW cm^-2. As a result, the current study's findings serve as the foundation for the creation of a broad band photodetector that can detect light in the visible to near infrared range.