Optimization of CdSe quantum dot concentration in P3HT:PCBM layer for the improved performance of hybrid solar cells

•An organic solar cell was fabricated with CdSe QDs mixed P3HT:PCBM layer.•The effect of CdSe QDs in active layer on light absorption was investigated.•Increasing concentration of QDs increased the charge transfer resulting in higher Jsc.•A 10% increase in power conversion efficiency was obtained due to the addition of 6 mg/mL CdSe QDs.•QDs helped in reduce trap-assisted recombination (monomolecular, bimolecular).

The improved performance of hybrid solar cells was obtained due to the effects of CdSe quantum dots (QDs) blended in the active layer. Different concentrations of CdSe QDs were mixed in the poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester (P3HT:PCBM) based active layer. We investigated the effects of CdSe QDs on the solar cell performances by ranging its concentration from 2 to 24 mg/mL. The charge transport in the active layer was improved at the optimized CdSe QDs concentration of 6 mg/mL. The solar cell with pristine active layers showed a 2.98% power conversion efficiency while that with 6 mg/mL CdSe QDs blended in layer showed a higher power conversion efficiency of 3.35% under AM 1.5G illumination. Analysis of recombination mechanism using the current density–voltage (J–V) characteristic at various light intensities was also performed.

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