Tao Yu

Thermal evaporation of perovskite films holds considerable promise for the scalable manufacturing and pixel patterning of perovskite light-emitting diodes (PeLEDs). However, the performance of evaporated PeLEDs remains inferior to their solution-processed counterparts due to the lack of effective strategies to regulate perovskite crystallization during vacuum deposition. Here we address this challenge and achieve precise control over crystallization pathways. Dual-amide additives suppress premature perovskite phase formation during deposition and decelerate crystallization kinetics during post-annealing. We realize thermally evaporated near-infrared PeLEDs with a maximum external quantum efficiency of 25.0% for emission at 805 nm, and a T ₅₀ lifetime of 23 h at a driving current density of 100 mA cm ⁻² . To show the advantages of thermal evaporation in pixelization, we realize monolithic dual-colour-emitting PeLEDs at 805 nm and 759 nm by integrating different PeLEDs on the same substrate and demonstrate dual-wavelength wearable pulse oximetry. This work provides insights into vacuum deposition crystallization dynamics and establishes a crystallization regulation methodology to advance evaporated perovskite optoelectronics.

Perovskite light-emitting diodes (LEDs) have attracted significant attention owing to their rapidly increasing external quantum efficiencies (EQEs). However, achieving bright and operationally stable perovskite LEDs remains a great challenge. Here, we reveal that the most commonly used surface modifier of zinc-oxide (ZnO) electron-transport layer, polyethylenimine ethoxylate (PEIE), inhibits the perovskite nucleation by inducing in situ chemical reactions of perovskite precursor components, forming thermally unstable interfacial species and reducing long-term operational stability of resultant devices. We develop a surface-engineering strategy by using an ether-based polymer modifier to regulate perovskite crystallization kinetics and simultaneously suppress ZnO-induced deprotonation during long-term device operation. As a result, the optimized near-infrared (NIR) perovskite LEDs exhibit a maximum EQE of 24% and a peak radiance of 539 W sr–1 m–2, along with significantly enhanced operational stability. Furthermore, partial substitution of FA with Cs confirms the generality of this strategy, yielding bright NIR devices with an operational half-lifetime of 561 h at 20 mA cm–2.

Tin (Sn)‐based perovskite near‐infrared (NIR) light‐emitting diodes (LEDs) show great potential for applications in night vision, biomedical sensing, and optical communications. However, their performance remains limited by uncontrolled crystallization and the facile oxidation of Sn ²⁺ . Here, we demonstrate a versatile buried‐interlayer strategy to effectively regulate the crystallization and suppress the Sn ²⁺ oxidation by constructing a two‐dimensional/three‐dimensional (2D/3D) heterodimensional structure. We reveal that strong interactions between the buried ligand layer, the perovskite precursor, and the underlying hole‐transport layer promote rapid nucleation, retard crystal growth, and induce a vertical dimensional gradient, leading to reduced defect density and enhanced radiative recombination. As a result, NIR Sn‐based perovskite LEDs achieve a record external quantum efficiency of 13.7% with a radiance of 103 W sr ⁻¹ m ⁻² . Furthermore, the buried‐interlayer strategy enables dual‐functional Sn‐based perovskite devices capable of both efficient light emission and photodetection, which are successfully integrated into a compact heart‐pulse monitoring system. Our work suggests a synergistic crystallization and dimensional‐regulation strategy for achieving high‐performance Sn‐based perovskite optoelectronic devices.

The development of miniaturized and mechanically flexible wearable optical health monitoring requires compact, biocompatible optoelectronic devices. Thin film devices based on perovskites, capable of both light emission and detection functionalities, offer a promising route toward such integrated systems. However, most reported dual-functional perovskite devices rely on toxic lead-based compositions, limiting their applications in skin-contact and wearable devices. Here, we demonstrate a lead-free tin-based perovskite dual-functional device, enabled by a synergistic dual-additive strategy to suppress defects and improve film crystallinity. The resulting device exhibits high-efficiency emission (radiance: 142 W m−2 sr−1, EQE: 7.56%) and sensitive photodetection (detectivity 1.53 × 1012 Jones). By integrating two perovskite diodes on a single flexible substrate, we realize a monolithic pulse sensor capable of real-time heart-rate monitoring. This work establishes a lead-free, flexible perovskite platform for bio-optoelectronic sensing, offering a promising pathway toward next-generation wearable healthcare systems.

A multifunctional zwitterionic additive regulates crystallization, passivates defects, suppresses ion migration and relaxes residual stress in inverted perovskite solar cells, achieving 26.69% certified efficiency and excellent stability.

By shortening the Ir–O bond and maintaining a robust rutile [IrO ₆ ] framework, IrO ₂ (sub-2 nm) synergistically enhances both activity and stability, breaking the long-standing OER dilemma.

Pulsed-laser trapping of Ir in WO ₃ creates sub-nanometric IrWO _x solid solutions that enable PEM water electrolysis with ultra-low Ir loading.

Tin-based perovskite solar cells (TPSCs) have attracted significant attention due to their relatively competitive performance and environmentally benign characteristics. Small-molecule additive strategies have been extensively employed to enhance TPSCs' performance through crystallization modulation and defect passivation. However, most small-molecule additives exhibit lattice deformation or spontaneous desorption from perovskite, leading to accelerated device degradation under operational thermal/electrical stresses. In this work, a component-engineering crystallization modulation strategy is developed to improve the crystallinity without introducing extraneous additives. It not only accelerates precursor nucleation during spin-coating but also promotes the formation of a two-dimensional phase at the initial annealing stage, ultimately optimizing crystal orientation and improve crystallinity. It enables a marked efficiency enhancement from 10.22% to 13.49% in TPSCs, coupled with exceptional stability showing negligible efficiency degradation after 5800 h N₂ storage. This study provides critical insights into stabilizing tin-based perovskites through intrinsic material design, circumventing the stability limitations inherent in conventional additive-based approaches.

Perovskite solar cells have attracted much interest due to the very fast increasement of power conversion efficiency (PCE) as well as the low-cost solution processing, excellent absorption coefficient, long charge carrier diffusion length. To date, further improvement of PCE in perovskite solar cells is mainly limited by the open-circuit voltage (V _OC ). In previous studies, the origin of V _OC is usually explained by the energy band alignment theory. However, in some experiments, the V _OC does not change apparently when the band positions of electron or hole transport layers are changed. Therefore, the energy band alignment theory is not suitable to explain the origin of V _OC in perovskite solar cells, and it’s desirable to reveal the origin of V _OC to further improve the PCE of perovskite solar cells. Here, we develop a new method to simulate the interface charge transfer process in the all solid-state devices in working conditions by connecting perovskite/ETL half device with perovskite/HTL half device under simultaneous illumination. Reversible reduction reactions of Pb ²⁺ /Pb ⁰ and oxidation reactions of I ^- /I ₂ are observed on MAPbI ₃ surfaces under illumination, respectively. Moreover, the oxidation processes of Spiro-OMeTAD are also investigated by in situ FTIR and NMR. We find that the V _OC comes from the difference between the electrode potentials of Pb ²⁺ /Pb ⁰ and X ^- /X ₂ (X=I, Br) on perovskite surfaces. The results suggest that the origin of V _OC does not come from the energy band alignment but from the electrode potential alignment, which can offer new perspectives to improve the V _OC of perovskite solar cells.