In this research work, for the first time, stable high-performance inverted polymer solar cells (iPSCs) have been fabricated utilizing facile and low-cost intermittent spray pyrolysis (SP) technique to deposit transparent thin films of zinc oxide (ZnO) as electron interfacial transporting layer (ETL). The performed iPSCs have the structure of ITO/ZnO/PBDTTT-EFT:PC70BM/V2O5/Ag. The thickness diversity of the ETL layer was adjusted by varying the concentration of the ZnO precursor solution, while fixed thicknesses were fabricated for the other layers in the iPSCs. Moreover, the influence of the deposition techniques on the interface roughness, performance, and stability of the devices has been detected and discussed. By increasing the concentration of the ZnO precursor solution as well as the number of spraying running cycles, the thickness and roughness of the ZnO film increase. The highest power conversion efficiency (10%) of the fresh iPSCs with ZnO-SP was obtained by using a ZnO-precursor solution concentration of 1:4 in ethanol with 7 spraying running cycles. This efficiency is almost the same as the iPSCs fabricated ZnO-ETL by the laboratory-scale spin coating (SC) technique that was used as a reference. Furthermore, it was interesting to observe that the stability of the devices intermittently sprayed by ZnO-SP was higher than the controlled reference ones that were fabricated by ZnO-SC. Hence, deep insight studies have been carried out for the fresh and degraded iPSCs using dark current–voltage characteristics and impedance spectroscopy measurements to investigate the electrical parameters for the ZnO film obtained by the SP and SC techniques. The results indicated that the interface roughness between the ZnO and the active layers plays an important role in enhancing light trapping and the light absorbance inside the cell which increases the generated electric current as well as the stability of the devices.

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Finding an effective approach to suppress trap formation is a potential route for enhancing the performance of nonfullerene organic photovoltaic (NF‐OPVs) devices. Here, an extraordinary short‐circuit current density (JSC) value of 32.65 mA cm‐2 is achieved, higher than the state‐of‐the art NF‐OPVs reported, reaching a high power conversion efficiency (PCE) of 17.92%. This remarkable enhancement is exhibited through the fine‐tuning of PEDOT:PSS/PM6:Y7 films and interface morphologies via applying the prethermal treatment approach (Pre‐TT) to the devices, which exhibit JSC and PCE enhancement of 21% and 8%, respectively, compared to the pristine devices. Accordingly, the dependence of the JSC upon the Pre‐TT approach through a range of morphological, optical, electrical, and advanced transient measurements is investigated. The Pre‐TT‐based films are found to possess optimal smooth blend morphology with better dispersity owing to reduced domain size. Moreover, the measurements show that the optimized treated devices present higher exciton dissociation probabilities and generation rate of the free charge carriers, showing an ideal balanced electron/hole mobility that reveals the JSC and PCE enhancement. Hence, Pre‐TT approach provides a facile passivation strategy that reduces the trap state density of the blend film, improves interface charge transfer, allows balanced electron/hole mobility, and thus promotes device performance.

Fine tuning of blend morphology is a key factor that limits the performance of the bulk‐heterojunction organic photovoltaics (BHJ‐OPVs). Herein, the morphological control of the binary (PM6:Y7) and ternary (PM6:Y7:PC70BM) blends is conducted through 1‐chloronaphthalene (CN) solvent additive and thermal annealing (TA) treatment with respect to their influence on the photovoltaic performance. Moreover, a distinct study is accomplished on the optical and electronic properties of the treated and nontreated binary and ternary devices by external quantum efficiency measurements and impedance spectroscopy. The results indicate that these treatments affect the performance of the binary and ternary OPVs differently. Regarding the 2% CN addition, the current density of the binary devices is improved by ≈27%, whereas the fill factor of the ternary devices shows a pronounced increment of ≈22%. A contradictory behavior is exhibited by TA for the binary and ternary OPVs. The PCEs for binary devices (with/without CN) and 2% CN‐treated ternary ones are improved, while diminishing the PCEs of the ternary ones with 0% CN. Accordingly, the highest efficiencies of the binary and ternary OPVs are obtained due to the dual effect of 2% CN solvent additive along with the TA treatments.

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A ternary strategy has been demonstrated as being an effective method to improve the power conversion efficiency (PCE); however, general rules for materials selection are not fully comprehended. Herein, nonfullerene acceptor ITIC‐M and fullerene acceptor PC70BM possessing higher lowest unoccupied molecular orbital (LUMO) and good miscibility with nonfullerene acceptor Y7 are incorporated as third components in the state‐of‐the‐art of PM6:Y7 binary blend. As a result, the device PCE for both ternary devices improves from 16.46% for binary host to 17.73% and 17.67% for ITIC‐M‐ and PC70BM‐based ternary devices, respectively. The higher LUMO of the guest acceptor can play multiple roles to elevate the open‐circuit voltage such as reducing energy‐loss and reverse saturation current, creating less‐localized shallow trap sites along with suppressing charge recombination, and decreasing Urbach energy. Moreover, the good miscibility facilitates an alloy‐like phase in acceptors domain for efficient exciton dissociation and electron transport, which leads to improved short‐circuit current density and fill factor in ternary devices. The results provide a promising approach to realize high‐performance ternary organic solar cells by synergizing the compatible third component with host acceptor.

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