Slow group velocity of light, multiple internal scattering in disordered domains, and the open void structure in photonic crystals can be exploited to amplify light energy conversion in thin solar cells. In this study, amplification of solar energy conversion by light trapping was explored in Q-CdTe and type-II CdTe/CdSe quantum dot solar cells using TiO2 inverse opals (i-TiO2-o) with stop bands centered at 600 and 560 nm, in comparison with nanocrystalline TiO2 (nc-TiO2), in selenide electrolyte. Selenide was found to stabilize Q-CdTe relative to sulfide by scavenging the photohole faster than it attacked the lattice. Emission quenching measurements revealed a size-dependent binding constant of Se2- on Q-CdTe, 7-times greater at 2.3 nm Q-CdTe compared to 4 nm dots, leading to type-II CdTe/CdSe quantum dots. Gains in light energy conversion were measured at Q-CdTe/600-i-TiO2-o relative to Q-CdTe/nc-TiO2. A significant increase in light-to-current conversion was measured over a wide visible range after dipping in selenide and annealing, attributed to formation of type-II CdTe/CdSe, and was significantly greater for the green- and yellow-emitting dots on i-TiO2-o than on nc-TiO2. For instance, the incident photon-to-current conversion efficiency (%IPCE) at 600 nm was ca. 4-fold larger at 560-TiO2-o sensitized with green-emitting Q-CdTe after selenide treatment compared to nc-TiO2. The amplification in light energy conversion at the inverse opals relative to nc-TiO2 is attributed to light trapping in the photonic crystal and to its open structure.

Amplification of solar energy conversion in Q-CdTe and type-II CdTe/CdSe quantum dots sensitized titania photonic crystals in selenide electrolyte

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.