Solar Cells, Photodetectors, and Optical Sources from Infrared Colloidal Quantum Dots

Optoelectronic devices made via spin-coating of soft materials onto an arbitrary substrate enable ready integration, low cost, and physical flexibility. The use of solution-processed colloidal quantum dots offers the added advantage of quantum-size-effect timing of material bandgap. Timing across the near- and short-wavelength infrared (SWIR) spectral regions enables applications in fiber-optic communications, night vision and biomedical imaging, and efficient solar energy collection. Here we review progress in infrared solar cells, light sensors, and optical sources based on solution-processed materials. The latest solution-processed photovoltaics now provide 4.2% power conversion efficiencies in the infrared, placing them a factor of three away from enabling a doubling in overall solar power conversion efficiency of visible-wavelength solution-processed photovoltaics. The best solution-processed photodetectors now provide sensitivities of 10(13) Jones D* (normalized detectivity), exceeding the sensitivity of the best epitaxially grown SWIR photodetectors. Infrared optical sources, both broadband light-emitting diodes and, more recently, lasers, have now also been reported at 1.5 mu m.