Photovoltaic properties of bulk heterojunction devices based on CuI-PVA as electron donor and PCBM and modified PCBM as electron acceptor

In this paper, we have investigated the bulk heterojunction organic solar cells based on CuI — polyvinyl alcohol (CuI-PVA) nanocomposite as electron donor and [6,6] — phenyl C60 — butyric acid methyl ester (PCBM) or modified PCBM i.e. F as electron acceptor. The power conversion efficiencies (PCEs) of 0.46 % and 0.68 % were achieved for the photovoltaic devices based on as cast CuI-PVA:PCBM and CuI-PVA:F blend films, respectively. The higher PCEs of the organic solar cells based on F as electron acceptor resulted from the increase in both short circuit current (Jsc) and open circuit voltage (Voc), due to the increased absorption of F in visible region and its higher LUMO level. After thermal annealing, the PCEs of the organic solar cells were further increased to 0.54 % and 0.80 % for CuI-PVA:PCBM and CuI-PVA:F blends, respectively. The increase in the PCEs was mainly due to the increase in Jsc, which has been attributed to the improvement in hole mobility and broadening of the absorption band in the longer wavelength region. The improved hole mobility resulted in more balanced charge transport in the devices based on the thermally annealed blends.