Perovskite solar cells (PSCs) have seen remarkable progress in recent years, largely attributed to various additives that enhance both efficiency and stability. Among these, fluorine-containing additives have garnered significant interest because of their unique hydrophobic properties, effective defect passivation, and regulation capability on the crystallization process. However, a targeted structural approach to design such additives is necessary to further enhance the performance of PSCs. Here, fluoroalkyl ethylene with different fluoroalkyl chain lengths (CH₂CH(CF₂)_nCF₃, n = 3, 5, and 7) as liquid additives is used to investigate influences of fluoroalkyl chain lengths on crystallization regulation and defect passivation. The findings indicate that optimizing the quantity of F groups plays a crucial role in regulating the electron cloud distribution within the additive molecules. This optimization fosters strong hydrogen bonds and coordination effects with FA⁺ and uncoordinated Pb²⁺, ultimately enhancing crystal quality and device performance. Notably, 1H,1H,2H-perfluoro-1-hexene (PF₃) with the optimal number of F presents the most effective modulation effect. A PSC utilizing PF₃ achieves an efficiency of 24.05%, and exhibits exceptional stability against humidity and thermal fluctuations. This work sheds light on the importance of tailored structure designs in additives for achieving high-performance PSCs.

Metal-halide perovskite solar cells have garnered significant research attention in the last decade due to their exceptional photovoltaic performance and potential for commercialization. Despite achieving remarkable power conversion efficiency of up to 26.1%, a substantial discrepancy persists when compared to the theoretical Shockley–Queisser (SQ) limit. One of the most serious challenges facing perovskite solar cells is the energy loss incurred during photovoltaic conversion, which affects the SQ limits and stability of the device. More significant than the energy loss occurring in the bulk phase of the perovskite is the energy loss occurring at the surface-interface. Here, we provide a systematic overview of the physical and chemical properties of the surface-interface. Firstly, we delve into the underlying mechanism causing the energy deficit and structural degradation at the surface-interface, aiming to enhance the understanding of carrier transport processes and structural chemical reactivity. Furthermore, we systematically summarized the primary modulating pathways, including surface reconstruction, dimensional construction, and electric-field regulation. Finally, we propose directions for future research to advance the efficiency of perovskite solar cells towards the radiative limit and their widespread commercial application.

Perovskite single-crystal arrays have attracted intensive attention because of their great potentials for integrated optoelectronic devices. However, the traditional top-down lithography strategy requires complex processing and is detrimental to perovskite crystal structures, which is incompatible to directly pattern perovskite single crystals. Herein, we report a lithography-free method to realize the controllable growth of perovskite single-crystal arrays. Through introducing a printed hydrophilic-hydrophobic substrate into the crystallization system, the MAPbCl₃ single-crystal arrays with precise location and uniform size are effectively fabricated. This method can be applied to prepare diverse perovskite single-crystal arrays, including MAPbBr₃, CsPbCl₃, CsPbBr₃, Cs₃Cu₂I₅, Cs₃Bi₂I₉, and (BA)₂(MA)₃Pb₄I₁₁. The perovskite single crystals can be selectively grown on the electrodes to fabricate ultraviolet photodetectors. The strategy demonstrates a facile approach to fabricate large-scale perovskite single-crystal arrays and opens a pathway to produce diverse perovskite optoelectronic devices.

Perovskite materials are promising candidates for the next generation of wearable optoelectronics. However, due to uncontrolled crystallization and the natural brittle property of crystals, it remains a great challenge to fabricate large-scale compact and tough perovskite film. Here we report a facile method to print large-scale perovskite films with high quality for flexible photodetectors. By introducing a soluble polyethylene oxide (PEO) layer during the inkjet printing process, the nucleation and crystal growth of perovskite is well controlled. Perovskite films can be easily printed in large scale and patterned in high resolution. Moreover, this method can be extended to various kinds of perovskite materials, such as MAPbI₃ (MA = methylammonium), MA₃Sb₂I₉, and (BA)₂PbBr₄ (BA = benzylammonium). The printed perovskite films show high quality and excellent mechanical performance. The photodetectors based on the MAPbBr₃ perovskite films show a responsivity up to ~ 1, 036 mA/W and maintain over 96.8% of the initial photocurrent after 15, 000 consecutive bending cycles. This strategy provides a facile approach to prepare large-scale flexible perovskite films. It opens up new opportunities for the fabrication of diverse wearable optoelectronic devices.

Trap-mediated energy loss in the buried interface with non-exposed feature constitutes one of the serious challenges for achieving high-performance perovskite solar cells (PSCs). Inspired by the adhesion mechanism of mussels, herein, three catechol derivatives with functional Lewis base groups, namely 3, 4-Dihydroxyphenylalanine (DOPA), 3, 4-Dihydroxyphenethylamine (DA) and 3-(3, 4-Dihydroxyphenyl) propionic acid (DPPA), were strategically designed. These molecules as interfacial linkers are incorporated into the buried interface between perovskite and SnO₂ surface, achieving bilateral synergetic passivation effect. The crosslinking can produce secondary bonding with the undercoordinated Pb²⁺ and Sn⁴⁺ defects. The PSCs treated with DOPA exhibited the best performance and operational stability. Upon the DOPA passivation, a stabilized power conversion efficiency (PCE) of 21.5% was demonstrated for the planar PSCs. After 55 days of room-temperature storage, the unencapsulated devices with the DOPA crosslinker could still maintain 85% of their initial performance in air under relative humidity of ≈15%. This work opens up a new strategy for passivating the buried interfaces of perovskite photovoltaics and also provides important insights into designing defect passivation agents for other perovskite optoelectronic devices, such as light-emitting diodes, photodetectors, and lasers.