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This work designed and synthesized a novel D'-A-DA'D-A-D' typed fused-ring-conjugated small-molecule cathode interlayer material (named FY1) to fabricate high-efficiency inverted PSCs and mini-PSC modules. FY1 improves electron transport, reduces energy barriers, and is ethanol-soluble for easy processing. It increases PSCs' performance, achieving 23.72% PCE and 82.3% FF, and maintains 98.5% efficiency after 850 h. [Display omitted] • A conjugated small molecule was developed and used as a CIL in PSCs. • FY1 improves interfacial contact and electron extraction. • FY1 modification realizes the work function of Ag and reduces the energy barrier. • FY1 can enhance the device performance and stability of the PSC modules. Perovskite solar cells (PSCs) represent a highly promising photovoltaic technology wherein a low-work function metal cathode is essential for efficient electron collection. The effectiveness of PSCs is significantly enhanced by a well-designed cathode interface layer (CIL). Characterized by their simple structure and impressive modification capabilities, small-molecule CILs hold considerable commercial potential for advancing the performance of PSCs. Herein, we synthesized a conjugated small-molecule CIL, named FY1, for modulating the cathode interface of inverted PSCs to enhance the power conversion efficiency (PCE) and long-term stability. FY1 not only optimized the molecule/metal contact to reduce traps but also uniformly improved the efficiency and speed of extracting photogenerated electrons, facilitating their effective extraction at the cathode interface. FY1 modification reduced the work function of Ag, subsequently lowering the energy barrier for electron transfer from the electron transport layer to the external cathode metal. By employing FY1 as a CIL, a record-high PCE of 23.72 % and a fill factor of 82.3 % were achieved in inverted PSCs. Furthermore, FY1 modification increased the PCE of PSC modules with an active area of 14 cm2 to 21.8 %; after continuous illumination for 850 h, it retained approximately 98.5 % of the initial efficiency. These findings show that FY1 can assist in unlocking the full potential of this emerging photovoltaic technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • The synthesis process is customized for single-particle Ni-rich layered cathode materials. • Morphological engineering of cathode materials enhances the rate-capability and cycling stability. • Microcrack formation and particle fracture can be effectively suppressed during cycling. • All-solid-state-battery shows a high capacity retention of 84.9% at 0.5C after 150 cycles. A single-crystalline Ni-rich cathode material is synthesized for high-performance all-solid-state batteries (ASSBs). We customize the morphology and microstructure of the material by optimizing the synthesis process (particle size control and post-heat treatment) and demonstrate the advantages of single-crystalline cathode materials for practical use in ASSBs. The particle density and particle hardness of single-crystalline cathode materials with a particle size of 5 μm are considerably higher than those of the conventional polycrystalline cathode materials that are composed of spherical aggregates of submicron-scale primary particles. These structural features of the single-crystalline cathode materials improve the long-term cycling performance and rate capability of an ASSB configured with an argyrodite–Li 6 PS 5 Cl solid electrolyte. This is mainly attributed to the intimate interfacial solid–solid contacts and enhanced diffusion kinetics induced by the monolithic morphology of the single-crystalline cathode materials in the electrode. Moreover, undesirable microcrack formation and particle fracture in cathode materials are effectively suppressed during cycling. The feasibility of ASSBs configured with single-crystalline Ni-rich cathode materials is examined in detail. [ABSTRACT FROM AUTHOR]