Expanding photon upconversion to silicon nanocrystal light absorbers

Abstract

Silicon is an earth-abundant, inexpensive and non-toxic material. While decades of research have led to its prominence in the microelectronics industry, much less is understood about nanostructured silicon. The use of an indirect-gap material like silicon to absorb light for triplet fusion based photon upconversion proposed has no precedent and is fundamentally interesting. The benign nature of silicon will facilitate rapid adoption in biomedical applications where visible light must be delivered deep in tissue. The multi-excitonic processes investigated here may pave the way to using singlet fission to exceed the Shockley-Queisser limit in photovoltaics. In this talk, the structure property relationships governing triplet energy transfer between molecules and silicon colloids will be elucidated. Transient absorption experiments, in parallel with photon upconversion measurements using continuous wave irradiation, will reveal the mechanism of energy transfer. The relationship between the structural details and the optical properties will guide the rational design of silicon nanoparticle based light absorbers for photon upconversion.