Filter-Free Narrowband Photodetectors Employing Colloidal Quantum Dots

Tuning the electronic bandgap of quantum dots via the quantum size-effect enables the tailored spectral response of quantum dot photodetectors, light emitting diodes, and solar cells. Chemically synthesized colloidal quantum dot (CQD) provides an option to produce such quantum material in an inexpensive way. Here, we propose an approach to fabricate filter-free narrowband photodetectors in near-infrared and mid-infrared regions using PbS and HgSe CQD materials, respectively. The spectrally selective bandpass response is implemented by taking advantage of the carrier collection narrowing effect using a photodiode device architecture. Narrower bandpass response in near-infrared region is further achieved employing blended PbS CQDs with different sizes. The external quantum efficiency spectra of these CQD detectors are comprehensively studied using numerical calculation.