title: Efficient Infrared-to-Visible Upconversion with Subsolar Irradiance.
abstract: Third generation photovoltaics are inexpensive modules that promise power conversion efficiencies exceeding the thermodynamic Shockley-Queisser limit, perhaps by using up- or down-converters, intermediate band solar cells, tandem cells, hot carrier devices, or multiexciton generation. Here, we report the efficient upconversion of infrared to visible light at excitation densities below the solar flux. Colloidally synthesized core-shell lead sulfide-cadmium sulfide nanocrystals in combination with tetracene derivatives absorb near-infrared light and emit visible light at 560 nm with an upconversion quantum yield (QY) of 8.4 ± 1.0%, which is a factor of 4 lower than the maximum upconversion QY possible. This is achieved with 808 nm cw excitation at 3.2 mW/cm2, approximately three times lower than the available solar flux. The molecular and nanocrystal engineering here paves the way toward utilizing this hybrid upconversion platform in photovoltaics, photodetectors and photocatalysis.
authors: Department of Materials Science and Engineering and ‡Department of Chemistry, University of California , Riverside, California 92521, United States.
authors: Melika
authors: M
authors: Mahboub
authors: Department of Materials Science and Engineering and ‡Department of Chemistry, University of California , Riverside, California 92521, United States.
authors: Zhiyuan
authors: Z
authors: Huang
authors: Department of Materials Science and Engineering and ‡Department of Chemistry, University of California , Riverside, California 92521, United States.
authors: Ming Lee
authors: ML
authors: Tang
keywords: Dexter transfer; NIR upconversion; acene; core−shell semiconductor quantum dots; solar; triplets