Evaluation of Electron Donor Materials for Solution-Processed Organic Solar Cells via a Novel Figure of Merit

Organic photovoltaic (OPV) technology offers many advantages, although no commercial applications have been achieved after more than a decade of intensive research and development. Several challenges have yet to be overcome including high power conversion efficiency (PCE), good process-ability, low cost, and excellent long-term stability, and so on. In this article, these fundamental challenges are significantly addressed by surveying and analyzing a new merit factor for material applied accessibility containing three parameters: synthetic complexity, device efficiency, and photostability. Thirty-five donor small molecules are introduced to assess their synthetic accessibility. Furthermore, the PCEs and device photostability of these molecules are carried out, and further measured under one sun illumination within 200 h, respectively. Combining with the characteristics of these three factors, investigated molecules are ranked according to an industrial figure of merit (i-FOM), while some guidelines for the material design and synthesis are given. It is suggested that a PCE of >14% and an i-FOM of >20% via active material engineering are realistic for possible industry future of OPV. Along with the systematic study, it is believed that this i-FOM can be taken into consideration at an early stage of molecular design and provides valuable insight for efficient evaluation of photovoltaic materials for possible commercial applications.