Junction diodes in organic solar cells. (November 2017) - Mao, Peng
Abstract: Organic solar cells (OSCs) have attracted great attention in the past 30 years due to their easy solution-processed preparation and material tunability, which could lead to light-weight, low-cost and large-area flexible solar products. Despite the shortcomings of their inferior device stabilities, their power conversion efficiencies (PCE) grow quickly with the development of new materials, and have surpassed 12% recently. However, the advance of physics in OSCs lags well-behind that of PCE. From a long-term perspective, an in-depth and systematic comprehension of internal physics in OSCs is essential for a lasting development of the field. Junction diodes are fundamental device units and of course cornerstones for understanding physics in OSCs. Although they have been investigated carefully in recent years, there are lots of confusions in understanding them. Therefore, it is of great importance to provide an in-depth discussion on such junction diodes. Here the research progress and status for understanding junction diodes in OSCs are systematically summarized and discussed. Firstly, the fundamentals of semiconductor solar cells are introduced and the particularities of OSCs are briefed. Secondly, the architecture evolution together with the nature of the junction diodes is described. Then key factors that dominate the junction diodes in OSCs are listed and discussed. In the end, a brief conclusion is presented and suggestions for optimizing the junction diodes are proposed. Graphical abstract: Highlights: The fundamentals of semiconductor solar cells are carefully briefed. The junction diodes in organic solar cells are fullydiscussed. The factors dominating the junction diodes in OSCs are systematically analyzed.