Spherical Hole-Transporting Interfacial Layer Passivated Defect for Inverted NiO-Based Planar Perovskite Solar Cells...

In this study, we achieved a facile and low-cost (18-22 USD/g) synthesis of spiro[fluorene-9,9-phenanthren-10-one]-based interfacial layer materials (MSs; designated MS-PC, MS-PA, MS-OC, and MS-OA). Carbazoles and dimethylacridine substituents with an extended π-conjugation achieved through ortho- or para-orientations were used as donors at the spiro[fluorene-9,9'-phenanthren-10'-one] moiety. Highly efficient and stable inverted perovskite solar cells (PSCs) with the device architecture of ITO/NiO/MSs/perovskite/PC₆₁BM/BCP/Ag can be achieved to improve the surface morphology of NiO when MSs are adopted as the interfacial layer. During a morphological study, the ortho-orientated donor of MS-OC and MS-OA has spherical structures indicated that the films were smooth and that the films of perovskite deposited on them had large grain size and uniformity. The photoluminescence properties of the perovskite layers on the NiO/MSs were showed better hole-transporting capabilities than the bare NiO. The dual-functional interfacial layer has shown defect passivation effect, it not only improved the surface morphology of NiO but also enlarged the perovskite layer grain size. The best PSC device performance of the NiO/MS-OC was characterized by 22.34 mA cm^-2 short-circuit current density (J_sc), 1.128 V open-circuit voltage (V_oc), and 80.8% fill factor (FF), resulting in 20.34% power conversion efficiency (PCE). The NiO/MS-OC PSCs showed good long-term device stability, even retained the original PCE of 93.16% after 370 days under argon (25 °C). Owing to the superior perovskite morphologies of the NiO/MSs, the resulting devices outperformed the bare NiO-based PSCs.