Zero-Dimensional PbS Quantum Dot-InGaZnO Film Heterostructure for Short-Wave Infrared Flat-Panel Imager

There is a growing demand for human-eye-invisible short-wave infrared (SWIR) detection due to its potential in applications in areas such as medical diagnostics, environmental monitoring, and night vision. PbS colloidal quantum dots (QDs) are a promising light absorber for SWIR detection. Herein, we report on a PbS QD/InGaZnO (IGZO) heterostructure-based phototransistor and flat-panel imager for human-eye-safe SWIR photodetection and high-resolution imaging. Such hybrid phototransistors show good electrical performance and obvious photoresponse behaviors with a maximum responsivity of 104 A/W and specific detectivity of 1012 Jones under 1310 nm SWIR illumination. We found that PbS QD ligand molecules significantly impact the environmental stability. Phototransistors featuring a tetrabutylammonium iodide (TBAI) ligand exhibit excellent air stability with no serious degradation after exposure to air for 3 weeks, while phototransistors with ethanedithiol (EDT) ligands lose their SWIR detecting capability within 2 weeks. Such an improved air stability may be correlated with the TBAI ligand passivation effect that is confirmed by X-ray photoemission spectroscopy analyses. PbS QDs are patterned on the flexible IGZO transistor array by photolithographic lift-off method for implementing a more practical imaging pixel array. Furthermore, we demonstrate a prototype of 1.3 μm SWIR flat-panel image sensor array, establishing its potential application in advanced developments as a gate-tunable, highly sensitive, high-resolution, and large area flat-panel SWIR imager.