a) E gap was determined from the intersection of the EQE edge and the local EQE maximum; b) V oc was calculated from the measured J-V curves; c) V oc rad was calculated from FTPS and EL measurements; d) EQE EL is the EL quantum efficiency of the fabricated devices; e) Exp. ΔE 3 is calculated with the Equation (ΔE 3 = −kTln(EQE EL )).

Morphology optimization is critical for achieving high efficiency and stable bulk-heterojunction (BHJ) organic solar cells (OSCs). Herein, the use of 3,5-dichlorobromobenzene (DCBB) with high volatility and low cost to manipulate evolution of the BHJ morphology and improve the operability and photostability of OSCs is proposed. Systematic simulations reveal the charge distribution of DCBB and its non-covalent interaction with the active layer materials. The addition of DCBB can effectively tune the aggregation of PBQx-TF:eC9-2Cl during film formation, resulting in a favorable phase separation and a reinforced molecular packing. As a result, a power conversion efficiency of 19.2% (certified as 19.0% by the National Institute of Metrology) for DCBB-processed PBQx-TF:eC9-2Cl-based OSCs, which is the highest reported value for binary OSCs, is obtained. Importantly, the DCBB-processed devices exhibit superior photostability and have thus considerable application potential in the printing of large-area devices, demonstrating outstanding universality in various BHJ systems. The study provides a facile approach to control the BHJ morphology and enhances the photovoltaic performance of OSCs.

non-fullerene acceptors (NFAs), has dramatically improved the development of OPV cells. [3][4][5][6][7] Despite the high power conversion efficiency (PCE) of OPV cells, further improvement of their performance is still a core issue. [8][9][10][11][12] Compared with their inorganic counterparts, OPV cells still suffer from a relatively low photon utilization efficiency. [13][14][15] Material type and active layer morphology are two key factors that determine the photon utilization efficiency of OPV cells. [16][17][18] Photovoltaic materials not only determine the light absorption of the active layers but also affect the properties of the photogenerated excitons. Wide-bandgap donors and narrow-bandgap NFAs with large extinction coefficients and small exciton binding energies are widely used to prepare bulk heterojunctions (BHJs). [19][20][21] Furthermore, to efficiently convert the excitons into free charges, it is necessary to improve the efficiencies of charge separation and collection, which are mainly controlled by the morphology of the active layer. [22] Therefore, in addition to developing new materials, a suitable morphology is required to further improve the PCEs of OPV cells.Directly obtaining an ideal morphology using solutionprocessing methods is challenging and typically usually Efficient photon utilization is key to achieving high-performance organic photovoltaic (OPV) cells. In this study, a multiscale fibril network morphology in a PBQx-TCl:PBDB-TF:eC9-2Cl-based system is constructed by regulating donor and acceptor phase-transition kinetics. The distinctive phase-transition process and crystal size are systematically investigated. PBQx-TCl and eC9-2Cl form fibril structures with diameters of ≈25 nm in ternary films. Additionally, fine fibrils assembled by PBDB-TF are uniformly distributed over the fibril networks of PBQx-TCl and eC9-2Cl. The ideal multiscale fibril network morphology enables the ternary system to achieve superior charge transfer and transport processes compared to binary systems; these improvements promote enhanced photon utilization efficiency. Finally, a high power conversion efficiency of 19.51% in a single-junction OPV cell is achieved. The external quantum efficiency of the optimized ternary cell exceeds 85% over a wide range of 500-800 nm. A tandem OPV cell is also fabricated to increase solar photon absorption. The tandem cell has an excellent PCE of more than 20%. This study provides guidance for constructing an ideal multiscale fibril network morphology and improving the photon utilization efficiency of OPV cells.

Ternary strategy has been identified as a feasible and effective way to obtain high-efficiency organic solar cells (OSCs). However, for most ternary OSCs, the voltage loss (Vloss) lies between those...

All‐polymer solar cells (all‐PSCs) have received attention in recent years for their desirable properties in power conversion efficiency and long‐term operational stability. However, it is still a big challenge to acquire an “ideal” vertical‐phase distribution of polymer/polymer blends due to the non‐ideal molecular conformations and mixing behaviors. Herein, a ternary‐assisted sequential solution deposition (SSD) strategy is adopted to regulate the vertical compositional profile of all‐PSCs. A favorable acceptor(donor)‐enriched phase near the cathode(anode) can be obtained by a ternary‐assisted SSD strategy. With such a compositional profile, the exciton yield and carrier density can be enhanced by the vertical component gradient. Remarkably, the non‐geminate recombination is suppressed with an improved exciton diffusion length (15.36 nm) that delivers an outstanding power conversion efficiency over 16% of the ternary PM6/PY‐IT:PDI‐2T SSD devices. This work demonstrates the success of ternary‐assisted SSD strategy in reorganizing the vertical‐phase distribution, which provides a feasible route for a potential ternary device construction toward efficient all‐polymer photovoltaics.