High-Efficiency Large Area Flexible Organic Solar Cells

Abstract

Large area bulk heterojunction PV devices based on P3HT/PCBM have been realized on transparent plastic substrates, following an implementation procedure starting from small size individual cell on glass to end with 35 cm² modules on PET. The first step consisted in the optimization of elaboration parameters on individual cells of 0.28 cm² on PET starting from our standard procedure setup for glass substrates. PCE close to 4% with small dispersion on plastic substrates for cells of 0.28 cm² active area, compared to 5% on glass. Two module designs were then tested on both substrates of 5x5 cm²,varying the number of individual cells and the interconnection pattern. For glass module, with 12 individual cells on a 5x5 cm2 substrate we obtain PCE of 3.26 % (12.4 cm² active area). Larger modules with active area up to 35 cm2 exhibiting PCE of 2.8 % and open circuit voltage higher than 6V were also realized on glass, approaching the requirements for commercial electronic applications. On PET, record efficiencies of 2.8 % and 2.5% were obtained for active areas of 8.8 cm2 and 53 cm² respectively. The influence of the geometric parameters of the individual cells and their type of connection (parallel or series) on the module characteristics is also discussed.