High-performance organic solar cells enabled by the p-i-n structure and ternary strategy

Abstract

Organic solar cells (OSCs) have attracted much attention in recent years due to their solution processability, low cost processing, flexibility, etc. However, despite the rapid development in recent years, the commonly used bulk heterojunction (BHJ) structure requires careful optimization of phase separation. On the other hand, the layer-by-layer (LBL) strategy with a p-i-n structure can also achieve an ideal film morphology for OSCs, which is mainly attributed to the easy regulation of the vertical component distribution. In this work, a ternary LBL device is fabricated to further improve the device performance. Compared with the binary LBL device and BHJ device, the ternary LBL device exhibits improved charge separation, reduced energy loss, and ideal vertical phase separation and morphology. As a result, an outstanding power conversion efficiency (PCE) of 19.46% has been achieved with improvements in short circuit current density (J_SC), open circuit voltage (V_OC) and fill factor (FF). In particular, operational stability is increased by the combination of the ternary strategy and LBL structure, which induces a stable phase and morphology. This study demonstrates an efficient way to realize high performance and stable OSCs, which is conducive to the further development of OSCs.