Roles and Impacts of Ancillary Materials for Multi‐Component Blend Organic Photovoltaics towards High Efficiency and Stability

Organic photovoltaics (OPVs) are a promising next‐generation photovoltaic technology with great potential for wearable and transparent device applications. Over the past decades, remarkable advances in device efficiency close to 20 % have been made for bulk heterojunction (BHJ)‐based OPV devices with long‐term stability, and room for further improvements still exists. In recent years, ancillary components have been demonstrated as effective in improving the photovoltaic performance of OPVs by controlling the optoelectronic and morphological properties of BHJ blends. Herein, an updated understanding of polymer‐based blend OPVs is provided, and the role and impact of ancillary components in various blend systems are categorized and discussed. Lastly, a strategic perspective on the ancillary components of blend‐based OPVs for commercialization is provided. Ancillary components: This Minireview highlights the updated roles and impacts of ancillary components in blend organic photovoltaics (OPVs). Ancillary component engineering demonstrates an effective strategy to improve the efficiency and stability of devices. Based on current understanding of the key factors in blend OPVs, the detailed roles of ancillary components in light‐harvesting, energy loss, miscibility, and stability are systematically characterized and their impacts on the device are discussed.