Mini-modules and tandem organic solar cellsstrategies to improve device efficiency

Abstract

A detailed analysis in the limitation of device area for P3HT:PCBM based organic solar cells was carried out by current-voltage, charge extraction and transient photovoltage characterization. Moreover, large area single cell performance was compared to mini-modules of similar active area. As a result, a reduction in the series resistance was observed for the mini-modules improving thus device performance.A roll-to-toll compatible novel patterning technique based on surface modification was also developed for the patterning of the active layer. As a result, 400 ¿m and 120 ¿m width patterned lines were achieved for conventional and inverted architecture devices, respectively.In order to achieve high efficiency devices, alternative polymers were tested and optimized in photovoltaic devices. The optimization of the low band gap polymer known as PTB7 was shown in detail. Differences in the working performance of conventional an inverted architecture devices were deeply analyzed.Finally, materials with complementary absorption spectra were stacked together in tandem cells. The performance of devices connected in either series or parallel was studied. Theoretical models were also developed and results were compared to those achieved experimentally.