An universal morphology regulator for efficient and stable nonfullerene organic solar cells by π–π interaction

Abstract

Abstract The efficiency and stability have been the focus of research on non-fullerene batteries in recent years. In this work, a new phenamidazole-based small molecule material TPPI-TPE has been utilized as the third component to constuct ternary organic solar cells (OSCs). The introduction of TPPI-TPE can not only strengthen the light absorption of the blend films, but also optimize the morphology of the active layers. In PTB7-Th:ITIC system, when the doping ratio of TPPI-TPE is 10 wt%, the corresponding ternary device obtained the highest power conversion efficiency (PCE) up to 9.50%, which represented a ~20% enhancement in comparison with the control binary device (7.88%). In PTO2: IT-4F system, at the optimal ratio, the device achieved 13.59% PCE, which means TPPI-TPE can optimize device performance in a variety of systems. It's worth noting that the optimal ternary device possessed better thermal, light irradiation, and air stability than the binary device. When stored in the dark atmosphere without encapsulation at the temperature of ~25 °C and the humidity of ~23%, the PCE of the ternary device remained 81% of its original state after 10 days, while that of the binary device was only 43%. Our work provides a simple and effective way to further improving the efficiency and stability of binary non-fullerene solar cells.