Solution-Processed Light Sensors and Photovoltaics

Solution processed solar cells and photodetectors have been investigated extensively due to their potential for low-cost, high throughput fabrication. Colloidal quantum dots (CQDs) and conjugated polymers are two of the most promising materials systems for these applications, due to their processibility and their tunability, the latter achieved by varying their size or molecular structure. Several breakthroughs in the past year highlight the rapid progress that continues to be made in understanding these materials and engineering devices to realize their full potential. CQD photodiodes, which had already shown greater detectivity than commercially available photodetectors, have now reached MHz bandwidths. Polymer solar cells with near-perfect internal quantum efficiencies have been realized, and improved 3-D imaging of these systems has allowed theorists to link structure and function quantitatively. Organic photodetectors with sensitivities at wavelengths longer than 1 $\mu{\rm m}$ have been achieved, and multiexciton generation has been unambiguously observed in a functioning CQD device, indicating its viability in further improving detector sensitivity.