Room Temperature Bias-Selectable, Dual-Band Infrared Detectors Based on Lead Sulfide Colloidal Quantum Dots and Black Phosphorus

A single photodetector capable ofswitching its peak spectral photoresponsebetween two wavelength bands is highly useful, particularly for theinfrared (IR) bands in applications such as remote sensing, objectidentification, and chemical sensing. Technologies exist for achievingdual-band IR detection with bulk III-V and II-VI materials,but the high cost and complexity as well as the necessity for activecooling associated with some of these technologies preclude theirwidespread adoption. In this study, we leverage the advantages oflow-dimensional materials to demonstrate a bias-selectable dual-bandIR detector that operates at room temperature by using lead sulfidecolloidal quantum dots and black phosphorus nanosheets. By switchingbetween zero and forward bias, these detectors switch peak photosensitiveranges between the mid- and short-wave IR bands with room temperaturedetectivities of 5 x 10(9) and 1.6 x 10(11) cm Hz(1/2) W-1, respectively. To thebest of our knowledge, these are the highest reported room temperaturevalues for low-dimensional material dual-band IR detectors to date.Unlike conventional bias-selectable detectors, which utilize a setof back-to-back photodiodes, we demonstrate that under zero/forwardbias conditions the device's operation mode instead changesbetween a photodiode and a phototransistor, allowing additional functionalitiesthat the conventional structure cannot provide.

Automated summary

In this study, a bias-selectable dual-band IR detector operating at room temperature was demonstrated using lead sulfide colloidal quantum dots and black phosphorus nanosheets. By switching between zero and forward bias, the peak photosensitive range of the detector can be switched between the mid- and short-wave IR bands, with room temperature detectivities of 5 x 10(9) and 1.6 x 10(11) cm Hz(1/2) W-1, respectively. These are the highest reported room temperature values for low-dimensional material dual-band IR detectors to date.