Isogenous Asymmetric–Symmetric Acceptors Enable Efficient Ternary Organic Solar Cells with Thin and 300 nm Thick Active Layers Simultaneously

Abstract

Integrating desirable light absorption, energy levels, and morphology in one matrix is always the aspiration to construct high‐performance organic solar cells (OSCs). Herein, an asymmetric acceptor Y6‐1O is incorporated into the binary blends of acceptor Y7‐BO and donor PM6 to prepare ternary OSCs. Two isogenous asymmetric–symmetric acceptors with similar chemical skeletons tend to form alloy‐like state in blends due to their good compatibility, which contributes to optimizing the morphology for efficient charge generation and extraction. The complementary absorption of two acceptors helps to improve the photon harvesting of ternary blends, and the higher lowest unoccupied molecular orbital (LUMO) energy level of Y6‐1O offers the chance to uplift the mixed LUMO energy levels of acceptors. Combining the aforesaid benefits, the ternary OSCs with 10 wt% Y6‐1O produce a top‐ranked power conversion efficiency (PCE) of 18.11% with simultaneously elevated short‐circuit current density, open‐circuit voltage, and fill factor in comparison to Y7‐BO‐based binary devices. Furthermore, the optimized ternary OSCs with ≈300 nm active layers obtain a champion PCE of 16.61%, which is the highest value for thick‐film devices reported so far. This work puts forward an avenue for further boosting the performance of OSCs with two isogenous acceptors but different asymmetric structures.

Improved Current Density and Fill Factor of Non‐Fullerene Organic Solar Cells Prepared under Solvent Vapor Atmosphere

“…The molecules stacking of the PM6: Y6 active layer films with and without methanol vapor atmosphere were determined using grazing incidence wide‐angle X‐ray diffraction (GIWAXS) measurements, and the 2D GIWAXS patterns are shown in Figure 5e,f, the out‐of‐plane (OOP) and in‐plane (IP) linecut profiles of the 2D GIWAXS are shown in Figure S3, Supporting Information, the d‐spacing and the crystal coherence lengths (CCLs) are summarized in Table S1, Supporting Information. The CCLs of the diffraction peaks are evaluated according to the Scherrer equation: [ 36–38 ] CCL = 2π k /FWHM, where k is the shape factor typically with the value of 0.9, and FWHM is the full width at the half maximum. Both PM6: Y6 films show the π‐π stacking peak at 1.71 Å −1 in the OOP direction and the lamellar stacking peaks at about 0.30 Å −1 in the IP direction.…”

Charge transfer regulated by domain differences between host and guest donors in ternary organic solar cells

“…19 On the another hand, Wang et al incorporated an asymmetric symmetric acceptor of Y6-1O with a chemical skeleton similar to that of Y7-BO into T-OSCs, which formed an alloy-like state due to good compatibility and obtained a PCE of 18%. 20 It is worth noting that both the ratio and properties of the third component are different in the two devices, and regardless of whether the third component is the guest acceptor or guest donor and whether it is structurally similar or not, the PCE can be significantly improved.…”

Solution-processed and thickness-insensitive hole transport layer for high efficiency organic solar cells

“…Considerable efforts have recently been devoted to enhance the photovoltaic performance of the OSCs with thick active layers. 18,19 Nevertheless, high-efficiency devices based on thick charge transport layers are rarely reported. It is particularly essential to develop thickness-insensitive interface layers applicable for large-scale manufacturing of high-performance OSCs.…”