Printed large-area photovoltaic modules based on the small-molecules with different alkyl terminal chains

Abstract

Solution-processed organic semiconductors have a great potential for cost-competitive, large-area and high throughput mass production on mechanically flexible substrate. In particular, small molecules, which is one of the organic conjugated molecules, have several advantages such as well-defined molecular structure, high purity, and less batch-to-batch variations, making them a more suitable candidate for industrial application. Neverthelss, the small-molecule solar cells fabricated by roll-to-roll compatible printing methods is still beyond the interest in this field. In this study, slot-die printed small-molecule solar cells were fabricated with application into large-area photovoltaic modules. Furthermore, by using two small-molecules with different alkyl terminal chains, we compared the effect of alkyl terminal chain length on morphology, crystalline properties as well as processing conditions required to slot-die coating process. As a result, based on the optimized conditions, we could achieve the power conversion efficiency of 5.5% for large-area photovoltaic modules with an active area of 24 cm2. To the best our knowledge, this is the highest efficiency and largest area reported to date for small-molecules photovoltaic modules fabricated by roll-to-roll compatible printing techniques.