Xiaoming Wen

Persistent intermediate power‐law exponent (β) values in metal halide perovskites commonly occur across excitation regimes in which assignment to a single carrier‐population recombination limit becomes ambiguous. Their strong dependence on excitation conditions further indicates that excitation‐dependent photoluminescence cannot always be interpreted uniquely through a static Shockley‐Read‐Hall (SRH)‐bimolecular‐Auger recombination picture. Here, power‐dependent and time‐resolved photoluminescence measurements on methylammonium lead iodide (MAPbI ₃ , MA = CH ₃ NH ₃ ) thin films reveal correlated evolution of excitation scaling, delayed emission, and illumination‐history response under conditions that systematically modify vibrational dissipation and carrier‐relaxation pathways. These behaviors are described using a dual‐channel framework in which transient vibrational energy retention contributes to delayed radiative response. The results support an interpretation of PL superlinearity as an emergent, condition‐dependent response associated with coupled carrier‐lattice relaxation dynamics, rather than a simple transition between fixed recombination‐order limits. More broadly, these results show that β and photoluminescence quantum yield (PLQY) should not be treated as fixed intrinsic material constants, but as excitation‐conditioned observables shaped by the evolving relaxation environment, highlighting limitations in interpreting PL scaling laws as direct indicators of recombination pathways in soft semiconductors.

Cu and Au-modified TiO ₂ nanorod arrays prepared by electroless deposition and galvanic replacement exhibit enhanced photocatalytic degradation of Rhodamine B.

Organolead halide perovskites, with their exceptional optoelectronic properties and intrinsic defect tolerance, have emerged as promising candidates for photovoltaics and photocatalysis. Yet, their photocatalytic activity remains hindered by severe nonradiative charge recombination. Herein, we introduce copper (Cu) atoms into methylammonium lead iodide ((CH3NH3)PbI3) during synthesis, directing the transformation of irregular crystals into well-defined dodecahedra. Comprehensive characterizations reveal that Cu mediation significantly promotes charge separation and transfer, leading to a remarkable 60-fold enhancement in hydrogen evolution compared to pristine (CH3NH3)PbI3. When coupled with a Ru/H2–TiO2 cocatalyst, the Cu-mediated (CH3NH3)PbI3 (100 mg) delivers 1.29 mmol of H2 within 6 h under simulated sunlight (AM 1.5G, 100 mW cm–2) and achieves a solar HI-splitting efficiency of 1.21% with an irradiation area of π·cm2. This work not only demonstrates a record-level photocatalytic performance of halide perovskites, but also provides mechanistic insights into how composition modulation and crystallographic engineering can unlock their potential for solar-driven hydrogen generation.

Artificial photonic synapses (APSs) are emerging as promising components for next‐generation neuromorphic computing due to their low crosstalk and high bandwidth. However, existing APSs either exhibit short‐lived photoconductivity (volatile), suitable for transient signal processing but inadequate for memory, or non‐volatile states that lack the dynamic decay needed for adaptive learning. In this study, we break this dilemma by introducing a semi‐volatile APS based on a sulfur vacancy (Sv)‐engineered ZnIn ₂ S ₄ /MoS ₂ heterojunction, which exhibits dynamically adjustable multi‐photoconductivity states. At the heterojunction, a charge transfer interface (CTI) dynamically orchestrates the routing of photoexcited charges into long‐lived Sv traps. This optically gated process unlocks programmable memory times spanning from 10 to 10 ³ s, enabling a seamless transition from short‐term to long‐term synaptic plasticity, filling the gap between volatile and non‐volatile memory. Leveraging the distinguishable multi‐photoconductivity states, we demonstrate a high‐security information encryption system and a dynamic cryptographic authentication protocol. Furthermore, the device serves as a reservoir computing unit, achieving efficient handwritten digit recognition. This work not only presents an advanced synaptic device but also establishes a new paradigm of interface engineering for multifunctional neuromorphic computing and secure photonic communications.

Defect‐induced nonradiative recombination and poor operational stability remain major challenges for methylammonium lead iodide (MAPI) perovskite solar cells. Here, we demonstrate polyaniline (PANI) in its emeraldine base form as a multifunctional additive to simultaneously improve film quality, charge‐carrier dynamics, device performance, and stability of MAPI perovskites. PANI incorporation enhances crystallinity and grain size without altering the intrinsic bandgap (∼1.6 eV). X‐ray photoelectron spectroscopy reveals strong Lewis acid–base coordination between the amine/imine groups of PANI and undercoordinated Pb ²⁺ defect sites, leading to effective defect passivation. Consequently, PANI‐modified films exhibit enhanced optical absorption, increased photoluminescence intensity, and prolonged charge‐carrier lifetimes. The optimized MAPI_30 film shows an increase in average carrier lifetime from 813.4 to 971.6 ns, indicating suppressed nonradiative recombination. Interfacial PL/TRPL studies further confirm efficient electron extraction at the perovskite/TiO ₂ interface. These improvements translate into enhanced device performance in HTL‐free perovskite solar cells, achieving a power conversion efficiency of 11.55% and an open‐circuit voltage of 1.04 V, compared to 9.41% for pristine MAPI. Moreover, PANI‐modified films exhibit excellent thermal stability at 85°C for 48 h and strong photostability under continuous illumination. This work establishes polyaniline as a simple and scalable strategy for developing efficient and durable perovskite solar cells.

The advancement of scintillators is of pivotal significance in X‐ray detection and imaging technologies, with widespread applications spanning security inspection, manufacturing quality control, medical diagnostics, and frontier scientific instruments. In recent years, metal halide perovskites and their derivatives have attracted considerable research interest as promising scintillators, attributed to their superior optoelectronic properties. Notably, zero‐dimensional (0D) copper halide Cs ₃ Cu ₂ I ₅ crystals have emerged as a promising candidate for next‐generation scintillation materials, owing to their near‐unity quantum yield, facile synthesis process, and excellent stability against humidity and X‐ray irradiation. This review first summarizes the crystalline structure of Cs ₃ Cu ₂ I ₅ and its two intrinsic emission mechanisms. Subsequently, it discusses the progress in X‐ray scintillation imaging performance of Cs ₃ Cu ₂ I ₅ ‐based nanocrystals and single crystals. The review then elaborates on the underlying mechanisms of metal ion doping (including Tl ⁺ , In ⁺ , Mn ²⁺ , alkali metals, and alkaline earth metals) in tailoring the optoelectronic properties of Cs ₃ Cu ₂ I ₅ crystals for scintillation applications. Finally, it highlights the emerging application prospects of Cs ₃ Cu ₂ I ₅ crystals, such as dual‐energy X‐ray imaging, multi‐energy X‐ray linear‐array detectors, and computed tomography imaging.

We report the first observation of illumination-induced transparency (IIT) in two-dimensional Ruddlesden-Popper halide perovskite single crystals. Under continuous excitation, the crystal becomes progressively transparent to its own photoluminescence (PL), particularly near the absorption edge where reabsorption is initially strong. The effect evolves over seconds, shows an excitation fluence threshold and persistence. We attribute IIT to the activation of lattice energy reservoirs (LERs), which are spatially non-uniform nanodomains that store phonon energy as elastic potential under optical excitation. These LERs enable subgap carrier upconversion thus generate photon gain that compensates the intrinsic absorption. The effect reveals a previously unrecognized optoelectronic behavior in 2D perovskites, governed by dynamic lattice–carrier interactions rather than electronic band filling. This phenomenon demonstrates a new light–matter interaction regime in perovskites and highlights LERs as optically accessible energy gateways. Our findings suggest new routes toward photon-recycling, upconversion, and reconfigurable photonic materials based on soft-lattice semiconductors.

Metal halide perovskites (MHPs) have emerged as promising materials for next-generation optoelectronic technologies, owing to their remarkable photophysical properties such as tunable bandgaps, long carrier diffusion lengths, and high radiative efficiencies. While light-induced degradation pathways, ion migration, defect formation, and phase segregation have been extensively studied, an equally critical yet underrecognized phenomenon is the reversible enhancement of photoluminescence (PL) under continuous illumination. This anomalous brightening behaviour challenges prevailing degradation-centric narratives and suggests a constructive light–matter interaction. Such effects can be leveraged to enhance photovoltaic parameters, such as the open-circuit voltage (V_oc) and fill factor (FF), offering new routes for optimizing perovskite device performance under illumination. However, the physical origins of this effect remain fragmented across the literature, lacking a cohesive theoretical framework. This review critically evaluates the proposed mechanisms behind PL enhancement, including defect passivation, ionic redistribution, and lattice dynamics, and introduces a unifying conceptual model based on lattice energy reservoirs (LERs), metastable, phonon-rich states that transiently store and recycle vibrational energy to re-activate trapped carriers. This framework explains key unresolved phenomena such as reversible PL gain, subgap emission, and excitation-fluence-dependent behaviour. By situating these insights within the mixed ionic–electronic nature of MHPs, we show how illumination can act not only as a stressor, but as a functional tuning parameter. This perspective offers new pathways for engineering light-responsive, high-performance, and more stable perovskite-based optoelectronics.