Light harvesting enhancement toward low IPCE region of semitransparent polymer solar cells via one-dimensional photonic crystal reflectors

•Light harvesting is enhanced toward low IPCE region(400–500 nm).•A high efficiency of 4.84% with an enhancement of 14.2% is obtained.•The average transmittance is 25.4% in visible range(400–700 nm).

In this study, we demonstrate a light harvesting method to achieve efficient semitransparent polymer solar cells (STPSCs) based on PCDTBT: PC70BM by employing one-dimensional photonic crystals (1DPCs) as reflector. The 1DPCs were constructed by N pairs of WO3/LiF, a pair means a combination of WO3 and LiF, including a layer of WO3 film and a layer of LiF film. By optimizing the number of pairs, a 1DPC with high reflectance region (400–500 nm), which is exactly matched with the weak region of the (incident photon-to-electron conversion) IPCE spectrum of the reference STPSC is obtained. In contrast, the excellent STPSC with 8 pairs of 1DPC exhibited a high efficiency about 4.84% and hold an average transmittance of 25.4% in the visible range (400–700 nm).

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