Planar perovskite solar cells made entirely via solution-processing at low temperatures (<150 °c) offer promise for simple manufacturing, compatibility with flexible substrates, and perovskite-based tandem devices; however, they require an electron-selective layer that performs well with similar processing. we report a contact passivation strategy using chlorine-capped tio2 colloidal nanocrystal (nc) film that mitigates interfacial recombination and improves interface binding in low-temperature planar solar cells. we fabricated solar cells with certified efficiencies of 20.1% and 19.5% for active areas of 0.049 and 1.1 square centimeters, respectively, achieved via low-temperature solution processing. solar cells with efficiency>20% retained 90% (97% after dark recovery) of their initial performance after 500 hours continuous room-temperature operation at their maximum power point under one-sun illumination.

Science 02 Feb 2017:
DOI: 10.1126/science.aai9081

http://science.sciencemag.org/content/early/2017/02/01/science.aai9081