High-performance perovskite film with superior internal and surface qualities is critical for perovskite solar cells (PSCs) but hardly achievable due to the rapid crystallization rate of perovskite itself. Herein, a novel technique by in situ manipulating perovskite crystal growth and modifying the surface properties is developed using organic passivating agent-assisted polydimethylsiloxane membrane as a facial mask (FM) of perovskites. By placing the perovskite-precursor films with their faces toward the designed FM during thermal annealing, a favorable microenvironment is constructed for incubating high-quality perovskite films with smooth surface, enhanced vertical orientation of (100) plane, and well-adjusted interfacial energy levels. With this versatile FM incubation technique, efficient PSCs for both methylammonium (MA)-based and formamidinium (FA)-MA-Cs mixed perovskite systems are facilely fabricated, delivering excellent humidity/thermal stabilities and promising efficiencies up to 21.4% with an improved open-circuit voltage of 1.15 V in MA-based devices. This study not only provides a facile and efficient approach to rationally manage the perovskite growth process, but also reveals the fundamental characteristics of high-quality perovskite films comprehensively for the construction of efficient and stable PSCs.

Structural defects in the bulk and on the surface of the perovskite layer serving as trap sites induce nonradiative recombination losses, limiting the performance improvement of perovskite solar cells (PSCs). Herein, we report a trometamol-induced dual passivation (TIDP) strategy to fix both bulk and surface defects of perovskites, where the trometamol molecule can simultaneously act as chemical additive and surface-modification agent. Studies show that trometamol as an additive can effectively reduce ionic defects and enhance the grain size of perovskites through Pb 2+ /−NH 2 coordination bonds and I − /−OH hydrogen bonds. As a surface-modification agent, trometamol further passivates ionic defects at the upper surface of the perovskite layer. As a result of the TIDP approach, a remarkable efficiency augmentation from 17.25% to 19.17% and an optimized thermal stability under inert conditions have been realized. These results highlight the importance of the TIDP strategy in perovskite defect management for excellent photovoltaic properties, facilitating the fabrication of highperformance PSCs.

High-quality defect-free perovskite films exhibiting improved surface morphology are required for constructing highly efficient perovskite solar cells (PSCs). Incorporation of appropriate passivation molecules in perovskite films is a popular strategy to achieve this goal. Herein, the defect passivation effect of a series of photosensitive benzoyl derivatives on the perovskite layer is investigated through the comprehensive analysis of perovskite film and corresponding solar cells. Photosensitive molecules introduced with carbonyl groups considerably diminish the defects of Pb 2+ and MA + by forming either coordinate bonds or hydrogen bonds. The ultraviolet (UV) photoinitiation properties of benzoyl derivatives help sufficiently restrain the photodegradation of perovskites during device operation. In addition, photosensitive molecule-assisted passivation strategy effectively inhibits unwanted defect-assisted recombination, improving the power conversion efficiency (PCE) from 16.94% to 19.64%. Meanwhile, passivated devices exhibit considerably enhanced light stability, with >80% of the initial PCE maintained under continuous 1 sun illumination for 700 h. This approach aids in fabricating defect-free and UV-resistant perovskite-based photoactive layers for highly efficient and stable PSCs.

The growth of high-quality perovskite films is complicated by the fact of uncontrollable crystallization pathways from perovskite precursors. During solution processing, extensive undesired nonperovskite products including residual solvate intermediates are produced due to quick solvent evaporation, which will adversely affect the efficiency and stability of perovskite solar cells (PSCs). Herein, we developed a highly efficient phase-transition pathway using a polydimethylsiloxane (PDMS)-based facial mask (FM) incubation technique, which enables significant reduction of the perovskite crystallization rate and depression of perovskite aggregation behavior. A surprising finding reveals that this technique induces complete phase transition from solvate intermediates to the perovskite phase, thereby obtaining phase-pure perovskite film. Meanwhile, a high-quality perovskite film with a shiny smooth surface, decreased defect states, and alleviated lattice strain is achieved after utilizing the FM strategy. Consequently, the target-inverted PSCs deliver a respectable efficiency of ∼21% and superior stability in both shelf storage (over 3700 h with 90% of initial efficiency) and light soaking (over 1000 h with 80% of initial efficiency) conditions. Our work highlights the importance of eliminating residual solvate intermediates to construct high-quality perovskites with excellent phase purity for ongoing production of high-performance perovskite-based optoelectronic devices.

The increasing body of research on the special nanofibers based on high-performance aramids has created a demand for approachable surface engineering methods. Here, using polymerization-induced self-assembled (PISA) para-aramid nanofibers (PANF) as the substrate, we propose a step-by-step decoration strategy on surfaces without deprotonation on poly­(para-phenylene terephthalamide) (PPTA). This strategy uses a modular design of chemical reactions that can be separately used so that the surface chemicals are selectable from alkoxysilane, functional sesquisiloxane, and polymer chains. The reaction modules can also be run in combination, which gives the polyaniline and PANF composite nanofibers (PANI/PANF) additional electrical activity and photothermal conversion capability. The unique surfaces of nanofibers built through the PISA process are effective at spatially tailoring the surface reactions to maintain the one-dimensional (1D) geometry after multiple steps of decoration. However, the rheological behaviors of the nanofiber dispersion as well as the liquid wetting and mechanical properties of the corresponding films showed a distinct response to the variation on PANF surface molecules. Moreover, diverse applications of the films for barrier and light-to-heat conversion are also suggested and take advantage of the simple but flexible PISA preparation process.