Organic solar cells (OSCs) technology is regarded as one of the most promising sustainable and green energy sources for their promise as environmentally friendly and easily printable devices. [1-6] In recent years, bulk-heterojunction (BHJ) OSCs Organic solar cells (OSCs) have made rapid progress in terms of their development as a sustainable energy source. However, record-breaking devices have not shown compatibility with large-scale production via solution processing in particular due to the use of halogenated environment-threatening solvents. Here, slot-die fabrication with processing involving hydrocarbon-based solvents is used to realize highly efficient and environmentally friendly OSCs. Highly compatible slot-die coating with roll-to-roll processing using halogenated (chlorobenzene (CB)) and hydrocarbon solvents (1,2,4-trimethylbenzene (TMB) and ortho-xylene (o-XY)) is used to fabricate photo active films. Controlled solution and substrate temperatures enable similar aggregation states in the solution and similar kinetics processes during film formation. The optimized blend film nanostructures for different solvents in the highly efficient PM6:Y6 blend is adopted to show a similar morphology, which results in device efficiencies of 15.2%, 15.4%, and 15.6% for CB, TMB, and o-XY solvents. This approach is successfully extended to other donor-acceptor combinations to demonstrate the excellent universality of this method. The results combine a method to optimize the aggregation state and film formation kinetics with the fabrication of OSCs with environmentally friendly solvents by slot-die coating, which is a critical finding for the future development of OSCs in terms of their scalable production and high-performance.

Non-fullerene acceptors (NFAs) with vibrant superiority over fullerene derivatives have proved advantageous as a guest component in a ternary blend signifying improved photon harvesting. However, heterogeneity of NFA-based ternary blend morphology is very complex, and the optimization requires simultaneous considerations of molecular miscibility and electronic properties. We discuss the role of guest NFA for an eased optimization of ternary blend photoactive layer in four different ways. Our four-model prospect of component selection is driven by the well-matched intrinsic miscibility, electronic, and optical characteristics of organic materials. We analyze each model, modulating photoactive layer morphology toward efficient transfer, transport, and collection of charges along with their balanced dissociation and drifting. We believe a model-based selection of NFA and its organization as a guest in a complex ternary blend will serve as a guide for researchers to optimize thin film nanostructures, a route toward efficient larger-area ternary devices.

Sequential deposition has great potential to achieve high performance in organic solar cells due to the well-controlled vertical phase separation. In this work, double bulk heterojunction organic solar cells were fabricated by sequential-blade cast in ambient condition, which is higher than the corresponding binary devices. Probed by the in-situ grazing incidence X-ray diffraction and in-situ UV-vis absorption measurements, the seq-blade system exhibited a different tendency from each of binary devices during the film formation process. Due to the extensive aggregation of FOIC, the binary PBDB-T:FOIC film displayed a strong and large phase separation, resulting in the low current density (Jsc) and unsatisfactory PCE.

Power conversion efficiency (PCE) of organic solar cells (OSCs) has crossed the 18% mark for OSCs, which are largely fabricated by spin‐coating, and the optimal photoactive thickness is limited to 100 nm. To increase reproducibility of results with industrial roll‐to‐roll (R2R) processing, slot‐die coating coupled with a ternary strategy for optimal performance of large‐area, thick OSCs is used. Based on miscibility differences, a highly crystalline molecule, BTR‐Cl, is incorporated, and the phase‐separation kinetics of the D18:Y6 film is regulated. BTR‐Cl provides an early liquid–liquid phase separation and early aggregation of Y6, which slightly improves the molecular crystallinity and vertical phase separation of the ternary blends, resulting in high PCEs of 17.2% and 15.5% for photoactive films with thicknesses of 110 and 300 nm, respectively. The ternary design strategy for large‐area and thick films is further used to fabricate high‐efficiency flexible devices, which promises reproducibility of the lab results from slot‐die coating to industrial R2R manufacturing.

As a predominant fabrication method of organic solar cells (OSCs), casting of a bulk heterojunction (BHJ) structure presents overwhelming advantages for achieving higher power conversion efficiency (PCE). However, long‐term stability and mechanical strength are significantly crucial to realize large‐area and flexible devices. Here, controlling blend film morphology is considered as an effective way toward co‐optimizing device performance, stability, and mechanical properties. A PCE of 12.27% for a P‐i‐N‐structured OSC processed by sequential blade casting (SBC) is reported. The device not only outperforms the as‐cast BHJ devices (11.01%), but also shows impressive stability and mechanical properties. The authors corroborate such enhancements with improved vertical phase separation and purer phases toward more efficient transport and collection of charges. Moreover, adaptation of SBC strategy here will result in thermodynamically favorable nanostructures toward more stable film morphology, and thus improving the stability and mechanical properties of the devices. Such co‐optimization of OSCs will pave ways toward realizing the highly efficient, large‐area, flexible devices for future endeavors.