Ultrasensitive PbS quantum-dot-sensitized InGaZnO hybrid photoinverter for near-infrared detection and imaging with high photogain

Lead sulfide (PbS) quantum dots (QDs) have great potential in optoelectronic applications because of their desirable characteristics as a light absorber for near-infrared (NIR) photodetection. However, most PbS-based NIR photodetectors are two-terminal devices, which require an integrated pixel circuit to be practical photosensors. Here we report on PbS QD/indium gallium zinc oxide (InGaZnO, IGZO) metal oxide semiconductor hybrid phototransistors with a photodetection capability between 700 and 1400 nm, a range that neither conventional Si nor InGaAs photodetectors can cover. The new hybrid phototransistor exhibits excellent photoresponsivity of over 106 A W−1 and a specific detectivity in the order of 1013 Jones for NIR (1000 nm) light. Furthermore, we demonstrate an NIR (1300 nm) imager using photogating inverter pixels based on PbS/IGZO phototransistors at an imaging frequency of 1 Hz with a high output voltage photogain of ~4.9 V (~99%). To the best of our knowledge, this report demonstrates the first QD/metal oxide hybrid phototransistor-based flat panel NIR imager. Our hybrid approach using QD/metal oxide paves the way for the development of gate-tunable and highly sensitive flat panel NIR sensors/imagers that can be easily integrated. A hybrid near-infrared photoinverter based on lead sulphide quantum (PbS) dots and InGaZnO that exhibits a high photogain has been made. PbS quantum dots have promising properties for near-infrared detection, but two-terminal devices based on them require an integrated pixel circuit. Now, Do Kyung Hwang at Korea University of Science and Technology and co-workers have demonstrated a hybrid near-infrared detector that employs PbS quantum dots to sensitize InGaZnO. The detector covers a wavelength range of 700–1,400 nanometres, which is not covered by conventional photodetectors. It also exhibits an excellent photoresponsivity of over 106 amperes per watt. The researchers consider that this approach will open up the way to develop highly sensitive, flat-panel near-infrared sensors and imagers that are both gate tunable and readily integrable. We propose hybrid approach of two classes of PbS QD as NIR light absorber and IGZO as the photogenerated charges acceptor/transport semiconductor to create phototransistor for near infrared (NIR) detection/imaging. Such hybrid phototransistor shows photodetection capability between 700 and 1400 nm. We demonstrate a NIR (1300 nm) imager using photogating inverter pixel based on PbS/IGZO hybrid phototransistor.