A wide-bandgap π-conjugated polymer for high-performance ternary organic solar cells with an efficiency of 17.40

Although substantial progress has been made at increasing power conversion efficiencies (PCEs) the field of ternary organic solar cells (TOSCs) during the past few years, choice of π-conjugated polymers that exhibit strong complementary spectra and achieve high photovoltaic parameters (open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and PCE) simultaneously is limited. In this paper, TOSCs demonstrated a high PCE of 17.09% based on a π-conjugated polymer (named SiCl-BDT, bandgap ≈ 1.84 eV) as a third component (15 wt%) to the host binary system consisting of a PM7:Y7. The third component was used to achieve enhanced absorption coefficient (λmax = 5.5 × 104 cm−1) and more balanced charge carrier transport, frontier molecular orbital (FMO) energy levels, and blend miscibility, contributed to an improved FF of 70.38% and yielded an impressive Jsc of 27.37 mA/cm2 and Voc of 0.84 V. The PCE was higher than the host PM7:Y7 (15.13%) binary device. In addition, we found the photovoltaic performance of TOSCs could be further increased to a benchmark PCE of 17.40% using an interface engineering strategy. Thus, enables efficient charge transfer in TOSCs compared with that of without interlayer TOSCs, leading to high Jsc, Voc. The resulting encapsulation-free TOSCs showed excellent ambient and thermal stability. Accordingly, this work suggests that the use of a passivated electron transporting layer (ETL) and a π-conjugated polymer as a third component offers a promising means of overcoming the lower PCEs of OSCs. [Display omitted] •The devices were fabricated in binary and ternary organic solar cells (TOSCs).•The cascade LUMO alignment and complementary absorption improve the performance of TOSCs.•The PCE of SiCl-BDT incorporated with binary host device (PM7:Y7) TOSCs reached to 15.12%, 17.09%.•An improved efficiency of 17.40% was achieved in a TOSC device using 3-(1-pyridinio)-1-propanesulfonate as a ZnO-passivation layer.•PM7:SiCl-BDT:Y7 based devices exhibit good thermal and ambient stability.