Review on performance analysis of P3HT:PCBM-based bulk heterojunction organic solar cells

Abstract Due to their low production costs, small weight, printability, solution processing, and the possibility of using flexible substrates, organic solar cells (OSCs) exhibit strong potential to be used in future solar cell technology. Major specifications for the commercialization of OSCs are the long life span of OSC devices, enhanced environmental stability and a sufficiently high power conversion efficiency (PCE). The development of low energy gap organic polymers, transport materials and multi-layer system architecture has been effective in achieving higher PCE. However, overcoming environmental stability and sustaining a longer life span are a major challenge. The instability of OSCs is the dynamic mechanism, mostly induced due to the combined impact of oxygen, incident light, and ambient, as well as processing, temperature. Studies have reported that thermal annealing of the active layer tends to a shift in the phase morphology, which typically occurs either because of the vertical phase separation or because of the process of donor–acceptor phase segregation. In this paper, various factors that affect the performance of the OSC have been comprehensively studied. Factors such as thermal stress, vertical phase segregation, material composition and tradeoff between thickness and light absorption have been discussed. This paper mainly reviews the measures carried out to improve the efficiency of conventional polymer-fullerene-based bulk-heterojunction OSCs and reports the different techniques to address these issues.