Sequential deposition method processed ternary organic solar cells with efficiency of 17.92%

Bulk heterojunction (BHJ) organic solar cells (OSCs) have developed rapidly in recent years. However, the problems of BHJ OSCs such as difficulty in regulating morphology have limited its further development. Combining sequential deposition (SD) method and ternary strategy is an effective way to solve the above problems as well as achieve high-performance OSCs. Herein, we prepared SD devices based on D18-Cl/Y6 system, which possess a vertical distribution structure facilitating charge transmission and inhibiting bimolecular recombination. Compared with BHJ OSCs, the highest power conversion efficiency (PCE) of SD OSCs is increased from 16.54% to 17.16%. Moreover, highly crystalline small molecule BTR-Cl was introduced to the active layer, which further broadened the absorption spectrum of the main system, enhanced the crystallinity of molecules and improved the morphology of films. Ultimately, ternary OSCs based on SD structure obtain a best efficiency of 17.92%, with an open-circuit voltage (Voc) of 0.886 V, short-circuit current density (Jsc) of 26.97 mAcm−2, and fill factor (FF) of 75.11%. This work demonstrates that the ternary strategy combined with SD approach is an effective method to overcome the difficulty to regulate morphology and realize high-performance OSCs.