Quantum Dot Donor-Polymer Acceptor Architecture for a FRET-Enabled Solar Cell.

Abstract

Forster resonance energy-transfer (FRET)-based solution-processed solar cell is fabricated with cadmium sulfide (CdS) as the energy donor and poly[ N-9'-heptadecanyl-2,7-carbazole- alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) as the energy acceptor. Carbon dots (C-dots) deposited on carbon fabric are applied as a counter electrode. Although electron injection from CdS to PCDTBT is energetically disfavored, evidences for energy transfer between the two components of the cell are obtained in terms of FRET parameters with the relative quantum yield of donor CdS quantum dots (QDs) being ∼0.3, a Forster radius of ∼3.7 nm, and an energy-transfer efficiency of ∼55%. Power conversion efficiency (PCE) of the TiO2/PCDTBT cell without the donor is 0.23% and when coupled with donor CdS QDs, the ensuing TiO2/PCDTBT/CdS cell experiences a 23 time increment in PCE, reaching 5.3%. The complete FRET cell: TiO2/PCDTBT/CdS/ZnS-S2--C-dots/C-fabric produces a PCE of 7.42%, under 1 sun illumination. External quantum efficiency studies reveal an enhanced spectral response spanning from 300 to 670 nm, with 300 and 175% increases attained for the FRET-enabled TiO2/PCDTBT/CdS/ZnS photoanode compared with the TiO2/PCDTBT photoanode over the blue and green-red portions of the solar spectrum.