Photon energy transfer by quantum dots in organic–inorganic hybrid solar cells through FRET

Abstract

Organic–inorganic hybrid solar cells were fabricated with InP QDs (5 wt%) in a BHJ active layer (PTB7 + PC₇₁BM). InP QDs were distributed on the top of the hybrid active layer (BHJ + QDs), determined through XPS depth profiling and AFM analyses. InP QDs showed strong emission characteristics at λ_max = 650 nm in the PL spectra. They played an important role in increasing J_sc by Förster resonance energy transfer (FRET) to PTB7. The carrier recombination of the hybrid active layer (BHJ + QDs) was reduced by morphology control through introducing a PFN interlayer. The carrier mobility of the device with the hybrid active layer (BHJ + QDs) increased 1.5–1.58 times over that of the device with the BHJ active layer. By means of the synergy effect of InP QDs and the PFN interlayer, the PCE of the fabricated hybrid solar cells was enhanced from 4.9% (J_sc = 13.2 mA cm⁻², FF = 60.0%) to 8.4% (J_sc = 14.5 mA cm⁻², FF = 72.5%).