<br/>Triplet-triplet annihilation sensitized by colloidal nanocrystals can efficiently convert infrared photons into visible photons at incident intensities as low as 1 sun. A solid-state device consisting of thin films of lead sulfide nanocrystals and rubrene doped with an emissive dye converts from wavelengths beyond λ = 1 μm to λ = 610 nm at an efficiency of up to (7±1)% of absorbed photons. Outstanding challenges remain, however, in improving the absorption of incident light in solid state devices. Present technologies rely on a monolayer of nanocrystals to sensitize the upconversion, but the monolayer typically absorbs only approximately 0.5% of incident light. Two solutions seem promising. First, we can improve the optical management within the device, concentrating light at the absorbing materials. Second, we can modify the sensitization process to enhance its thickness and optical cross section. We describe our recent work on both topics. We show weak optical microcavities with enhanced absorption at wavelengths of interest, and relate our understanding of energy transfer at the crucial inorganic/organic interface. We conclude with a perspective on the adoption of triplet exciton annihilation in photovoltaic and sensing applications. <br/>

Solid-state infrared-to-visible upconversion sensitized by colloidal nanocrystals

254th National Meeting (2017)

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