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Abstract Quasi‐2D metal halide perovskite light emitting diodes (PeLEDs) have attracted a lot of attentions in recent years, while their potential applications in displays and lighting are limited by the device stability. Although defect passivation in PeLEDs is an effective method to ameliorate the unstable problem, the underlying mechanisms need to be further explored. Herein, organic spacer cations with different charge distributions and formation energies in quasi‐2D CsPbBr3 perovskites are utilized to unravel the defect passivation mechanisms, including phenylmethanamine, 2‐phenylethanamine bromide, and 4‐phenylbutylammonium. The experimental findings and density functional theory calculation reveal that the defect passivation occurs by the electrostatic interaction between defective PbBr64− octahedrons and proper organic spacer cations during the annealing process, particularly at the grain boundaries. The thermal stability of the perovskite films and device performance are improved after the effective defect passivation process. The exploration of the defect passivation process in perovskites will be beneficial to the development of high‐performance PeLEDs.

Photodiode‐type solar‐blind photodetectors (SBPDs) with the self‐powered feature hold great promise for applications in unattended secure communication, flame detection, and missile warning. However, the responsivity of SBPDs is usually limited due to the severe solar‐blind (SB) light extinction in substrates and charge transport layers. Herein, a spectrally selective hole extraction structure (SHE) is proposed for high‐efficiency perovskite SBPDs. The SHE consisting of a tandem Fabry–Perot cavity and energy‐level‐matched hole transport layer endows the device with narrowband absorption in the SB region and optimized charge extraction capability from the CsPbI2Br perovskite. The optimized SHE exhibits a peak transmittance of 27% at 255 nm and a half maximum at full width of 28 nm. Under SB light illumination, the champion device achieves a responsivity of 56.20 mA W−1 and a detectivity (D*) of 2.86 × 1013 Jones, which are the record values among the reported results. The approach demonstrated here paves the way for the optical and electrical design of perovskite photodetectors with spectrally selective detection. [ABSTRACT FROM AUTHOR]

Quasi‐two‐dimensional (quasi‐2D) perovskites are emerging as efficient emitters in blue perovskite light‐emitting diodes (PeLEDs), while the imbalanced crystallization of the halide‐mixed system limits further improvements in device performance. The rapid crystallization caused by Cl doping produces massive defects at the interface, leading to aggravated non‐radiative recombination. Meanwhile, unmanageable perovskite crystallization is prone to facilitate the formation of nonuniform low‐dimensional phases, which results in energy loss during the exciton transfer process. Here, we propose a multifunctional interface engineering for nucleation and phase regulation by incorporating the zwitterionic additive potassium sulfamate into the hole transport layer. By using potassium ions (K+) as heterogeneous nucleation seeds, finely controlled growth of interfacial K+‐guided grains is achieved. The sulfamate ions can simultaneously regulate the phase distribution and passivate defects through coordination interactions with undercoordinated lead atoms. Consequently, such synergistic effect constructs quasi‐2D blue perovskite films with smooth energy landscape and reduced trap states, leading to pure‐blue PeLEDs with a maximum external quantum efficiency (EQE) of 17.32 %, spectrally stable emission at 478 nm and the prolonged operational lifetime. This work provides a unique guide to comprehensively regulate the halide‐mixed blue perovskite crystallization by manipulating the characteristics of grain‐growth substrate. [ABSTRACT FROM AUTHOR]

Perovskite light‐emitting diodes (PeLEDs) are emerging as promising candidates for new‐generation high‐definition displays with excellent color purity and low power consumption. Nevertheless, the massive defects at grain boundaries and severe interfacial exciton quenching are critical challenges that hinder the commercialization process of PeLEDs. Herein, a novel and feasible strategy of interfacial molecule control is demonstrated by employing a bifunctional material with abundant phosphine oxide groups to induce strong interaction and exciton management between the perovskite and electron‐transport layers (ETLs). This modification layer is capable of passivating the surface crystal defects and blocking the interfacial exciton transfer simultaneously, contributing to minimized energy loss at the interface. Consequently, the modified PeLEDs with green (at 513 nm), blue (at 488 nm), and red (at 666 nm) emissions achieve maximum external quantum efficiencies of 18.8%, 12.6%, and 12.3%, respectively. This study reveals the importance of interfacial molecule control for reducing the energy loss in PeLEDs. [ABSTRACT FROM AUTHOR]

Perovskite Light‐emitting diodes (PeLEDs) have emerged as a promising technique for future high‐definition displays due to their outstanding electroluminescent characters. However, the development of blue PeLEDs toward practical applications is seriously hindered by their inferior performance, which mainly arises from the detrimental halide ionic behavior and thus severe nonradiative recombination in mixed‐halide blue perovskite materials. Herein, efficient sky‐blue PeLEDs featuring spectrally stable emission at 483 nm are realized by employing bifunctional passivators of Lewis‐base benzoic acid anions and alkali metal cations to simultaneously passivate the under‐coordinated lead atoms and suppress halide ion migration. A decent external quantum efficiency (EQE) of 16.58% and a maximum EQE of 18.65% are achieved, which is further boosted to 28.82% through the optical outcoupling enhancement. This work demonstrates unique insight into the generality and individuality of this category of benzoates and puts forward a feasible guidance in choosing appropriate additives for efficient perovskite materials. [ABSTRACT FROM AUTHOR]

Reduced‐dimensional perovskite light‐emitting diodes (PeLEDs) have shown great potential in solution‐processed high‐definition displays. However, the inferior electroluminescent (EL) performance of blue PeLEDs has become a huge challenge for their commercialization. The inefficient domain control [number of PbX6− layers (n)] and deleterious phase segregation make the blue PeLEDs suffer from low EL efficiency and poor spectral stability. Here, a rational strategy for perovskite crystallization control by adjusting the precursor concentration is proposed for improving phase distribution and suppressing ion migration in reduced‐dimensional mixed‐halide blue perovskite films. Based on this method, efficient sky‐blue PeLEDs exhibit a maximum external quantum efficiency (EQE) of 8.5% with stable EL spectra at 482 nm. Additionally, spectrally stable pure‐blue PeLEDs at 474 and 468 nm are further obtained with maximum EQEs of 4.0% and 2.4%, respectively. These findings may provide an alternative scheme for manipulating perovskite crystallization dynamics toward efficient and stable PeLEDs. [ABSTRACT FROM AUTHOR]

Halide perovskite materials are emerging as a new promising semiconductor display material owing to their excellent optical and electrical properties. Highly efficient blue perovskite light‐emitting diodes (PeLEDs) are the basis for full‐color displays and solid‐state lighting applications, but their efficiency and stability still lag far behind the red and green analogs. This review focuses on the key effect factors and novel strategies for blue emission PeLEDs. In detail, first effective strategies to obtain blue emission perovskite are discussed, and then the recent progress and strategies in blue emission PeLEDs, including the physical properties and significant improvements based on different structural perovskite materials are systematically elucidated. Finally, the main challenges relating to efficiency, stability, lead toxicity, and fabrication techniques in blue emission PeLEDs are summarized, and the promising research avenues in the future are discussed. [ABSTRACT FROM AUTHOR]

Metal halide perovskite (MHP) materials have shown great advantages for the next‐generation optoelectronic devices, especially for light‐emitting diodes (LEDs), on account of their outstanding photoelectric properties and facile solution processability. However, the performances of red perovskite LEDs (PeLEDs) are not ready for commercialization, presumably due to the instability both of the emission spectra and operation conditions, and the toxicity of lead ions. In this review, the structures, physical properties, and preparation approaches of red emissive perovskite materials are first introduced, including 3D bulk perovskites, 2D and quasi‐2D perovskites, and colloidal perovskite nanocrystals (NCs). In addition, several strategies that contribute to the recent development and achievement of red PeLEDs are summarized in detail, mainly involving component engineering, dimension, and phase distribution modulation, ligand engineering, additive engineering, interfacial engineering, and strategies for the light out‐coupling device structure. Moreover, the challenges and corresponding solutions are discussed from three aspects of spectral stability, operational stability, and lead‐free red PeLEDs. Finally, the conclusion and outlook on the promising future of the red PeLEDs are raised. [ABSTRACT FROM AUTHOR]

Polarization‐sensitive photodetectors are gaining numerous attention since polarization detection is important in geological remote sensing, atmospheric monitoring, military recon, and medical examination. Among various reported photoactive materials for photodetectors, metal halide perovskites have outstanding advantages such as tunable band gaps, excellent optoelectronic properties, and easy fabrication. Moreover, the characteristics of crystal structure anisotropy and controllable growth orientation of perovskite crystals endow the perovskite photodetector with the ability to identify light polarization states. This review outlines the recent research progress of perovskite photodetectors on polarization‐sensitive detection. Firstly, key device parameters of polarization‐sensitive detection are introduced. Then, the recent progress of polarization‐sensitive perovskite detectors in the field of linear and circular polarization is reviewed according to the different principles of polarization response. Finally, the challenges of polarization‐sensitive perovskite photodetector are discussed. [ABSTRACT FROM AUTHOR]

Perovskite light‐emitting didoes (PeLEDs) have shown considerable potential in solution‐processable display applications. However, the performance of blue PeLEDs in terms of efficiency and stability hinders their practicality on account of severe trap‐mediated nonradiative recombination losses and halide phase segregation. To ameliorate these issues, mixed‐halide sky‐blue perovskite materials are strategically modulated through crystal defect passivation with a trifurcate isocyanate oligomer, which leads to the synergistical suppression of charge trap density and halide ion migration. The proposed approach enables the performance improvement for sky‐blue PeLEDs, exhibiting a peak external quantum efficiency of 14.82% and spectrally stable emission at 487 nm. In addition, prolonged operational lifetime and enhanced capability of moisture resistance are achieved simultaneously, approaching a half‐lifetime of ≈2900 s at an initial brightness of 178 cd m–2. [ABSTRACT FROM AUTHOR]

Quasi‐2D metal halide perovskite light emitting diodes (PeLEDs) have attracted a lot of attentions in recent years, while their potential applications in displays and lighting are limited by the device stability. Although defect passivation in PeLEDs is an effective method to ameliorate the unstable problem, the underlying mechanisms need to be further explored. Herein, organic spacer cations with different charge distributions and formation energies in quasi‐2D CsPbBr3 perovskites are utilized to unravel the defect passivation mechanisms, including phenylmethanamine, 2‐phenylethanamine bromide, and 4‐phenylbutylammonium. The experimental findings and density functional theory calculation reveal that the defect passivation occurs by the electrostatic interaction between defective PbBr64− octahedrons and proper organic spacer cations during the annealing process, particularly at the grain boundaries. The thermal stability of the perovskite films and device performance are improved after the effective defect passivation process. The exploration of the defect passivation process in perovskites will be beneficial to the development of high‐performance PeLEDs. [ABSTRACT FROM AUTHOR]

Regardless of the rapid advance on perovskite light‐emitting diodes (PeLEDs), the lack of long‐term operational stability hinders the practicality of this technology. Particularly, thermal management is indispensable to control the Joule heating induced by charge transport and parasitic re‐absorption of internally confined photons. Herein, a synergetic device architecture is proposed for minimizing the optical energy losses in PeLEDs toward high efficiency and long lifetime. By adopting a carefully modified perovskite emitter in combination with an improved light outcoupling structure, red PeLEDs emitting at 666 nm achieve a peak external quantum efficiency of 21.2% and an operational half‐lifetime of 4806.7 h for an initial luminance of 100 cd m‐2. The enhanced light extraction from trapped modes can efficiently reduce the driving current and suppress optical energy losses in PeLEDs, which in turn ameliorate the heat‐induced device degradation during operation. This work paves the way toward high‐performance PeLEDs for display and lighting applications in the future. [ABSTRACT FROM AUTHOR]

Efficient and stable blue emission of perovskite light‐emitting diodes (PeLEDs) is a requisite toward their potential applications in full‐color displays and solid‐state lighting. Rational manipulation over the entire electroluminescence process is promising to break the efficiency limit of blue PeLEDs. Herein, a facile device architecture is proposed to achieve efficient blue PeLEDs for simultaneously reducing the energetic loss during electron‐photon conversion and boosting the light outcoupling. Effective interfacial engineering is employed to manipulate the perovskite crystallization nucleation, enabling highly compact perovskite nanocrystal assemblies and suppressing the trap‐induced carrier losses by means of interfacial hydrogen bonding interactions. This strategy contributes to a high external quantum efficiency (EQE) of 12.8% for blue PeLEDs emitting at 486 nm as well as improved operational stability. Moreover, blue PeLEDs reach a peak EQE of 16.8% with the incorporation of internal outcoupling structures for waveguided light, which can be further raised to 27.5% by integrating a lens‐based structure for substrate‐mode light. These results verify the validity of this strategy in producing efficient and stable blue PeLEDs for practical applications. [ABSTRACT FROM AUTHOR]

While tremendous progress has recently been made in perovskite light‐emitting diodes (PeLEDs), large‐area blue devices feature inferior performance due to uneven morphologies and vast defects in the solution‐processed perovskite films. To alleviate these issues, a facile and reliable interface engineering scheme is reported for manipulating the crystallization of perovskite films enabled by a multifunctional molecule 2‐amino‐1,3‐propanediol (APDO)‐triggered "anchoring effect" at the grain‐growth interface. Sky‐blue perovskite films with large‐area uniformity and low trap states are obtained, showing the distinctly improved radiative recombination and hole‐transport capability. Based on the APDO‐induced interface engineering, synergistical boost in device performance is achieved for large‐area sky‐blue PeLED (measuring at 100 mm2) with a peak external quantum efficiency (EQE) of 9.2% and a highly prolonged operational lifetime. A decent EQE up to 6.1% is demonstrated for the largest sky‐blue device emitting at 400 mm2. [ABSTRACT FROM AUTHOR]

Metal halide perovskites are one of the most promising materials for optoelectronic applications owing to their unique optoelectronic properties. In the pursuit of achieving the efficient perovskite light‐emitting diodes (PeLEDs), the critical role of crystallization dynamics on luminescence properties of cesium lead bromide (CsPbBr3) perovskite films has been clarified based on the characterizations of in situ photoelectron spectroscopy, synchrotron‐based grazing incidence X‐ray diffraction, and device fabrication. The crystallinity and crystal orientation of CsPbBr3 perovskite films has been effectively controlled when tuning the underlayer of poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) with the ethanolamine modification. The fast crystallization with the formation of pure cubic phase (α‐CsPbBr3) reveals a substantial boost in luminance and device efficiency of PeLEDs, whereas the performance degradation occurs due to the phase transition from α‐CsPbBr3 to orthogonal phase (γ‐CsPbBr3) along with the appearance of PbBr2. The decomposition of organic additives in the perovskite films is a key factor that results in this phase transition, which changes the absorption and band gap as confirmed by the density functional theory calculation. These experimental and theoretical findings provide a better understanding of the crystallization dynamics of perovskite emitters and their influence on device performance by tuning the substrate properties. [ABSTRACT FROM AUTHOR]

Perovskite light‐emitting diodes (PeLEDs) are emerging candidates for the applications of solution‐processed full‐color displays. However, the device performance of deep‐blue PeLED still lags far behind that of their red and green counterparts, which is largely limited by low external quantum efficiency (EQE) and poor operational stability. Here, a facile and reliable crystallization strategy for perovskite grains is proposed, with improved deep‐blue emission through rational interfacial engineering. By modifying the substrate with potassium cation (K+) as the supplier of heterogeneous nucleation seeds, the interfacial K+‐guided grain growth is realized for well‐packed perovskite assemblies with high surface coverage and the controlled crystal orientation, leading to the enhanced radiative recombination and hole‐transport capabilities. Synergistical boost in device performance is achieved for deep‐blue PeLEDs emitting at 469 nm with a peak EQE of 4.14%, a maximum luminance of 451 cd m–2, and spectrally stable color coordinates of (0.125, 0.076) that matches well with the National Television System Committee (NTSC) standard blue. [ABSTRACT FROM AUTHOR]

Despite the rapid development of high-efficiency perovskite light-emitting diodes (PeLEDs) via material design and morphology control, a comprehensive evaluation of the power loss among various optical modes has seldom been conducted for the precise design of device architectures. Here, a quantitative analysis of light outcoupling efficiency (η out ) of PeLEDs is presented with the theoretical simulations by taking into account the key factors of refractive index and film thickness of various functional layers, and the emitter dipole orientation. For a planar PeLED, a rational design to enhance the η out is predicted by constructing multilayer stack in series of transparent electrode/high-index transport layer/perovskite emitter/low-index transport layer/reflective electrode. Furthermore, the role of photonic structures on the outcoupling management is explored, and the potential of a substantial increase in η out is demonstrated with an enhancement factor of over 1.75 by implementing a moth-eye nanostructure into the emitter. We anticipate that the findings shown here will provide the design guidelines for the optical optimization of PeLEDs. [ABSTRACT FROM AUTHOR]

Light management holds great promise of realizing high-performance perovskite solar cells by improving the sunlight absorption with lower recombination current and thus higher power conversion efficiency (PCE). Here, a convenient and scalable light trapping scheme is demonstrated by incorporating bioinspired moth-eye nanostructures into the metal back electrode via soft imprinting technique to enhance the light harvesting in organic-inorganic lead halide perovskite solar cells. Compared to the flat reference cell with a methylammonium lead halide perovskite (CH3NH3PbI3− x) absorber, 14.3% of short-circuit current improvement is achieved for the patterned devices with moth-eye nanostructures, yielding an increased PCE up to 16.31% without sacrificing the open-circuit voltage and fill factor. The experimental and theoretical characterizations verify that the cell performance enhancement is mainly ascribed by the broadband polarization-insensitive light scattering and surface plasmonic effects due to the patterned metal back electrode. It is noteworthy that this light trapping strategy is fully compatible with solution-processed perovskite solar cells and opens up many opportunities toward the future photovoltaic applications. [ABSTRACT FROM AUTHOR]x) absorber, 14.3% of short-circuit current improvement is achieved for the patterned devices with moth-eye nanostructures, yielding an increased PCE up to 16.31% without sacrificing the open-circuit voltage and fill factor. The experimental and theoretical characterizations verify that the cell performance enhancement is mainly ascribed by the broadband polarization-insensitive light scattering and surface plasmonic effects due to the patterned metal back electrode. It is noteworthy that this light trapping strategy is fully compatible with solution-processed perovskite solar cells and opens up many opportunities toward the future photovoltaic applications. [ABSTRACT FROM AUTHOR]

Metal halide perovskites, a class of crystalline semiconductors with unique optical and electronic properties, are emerging as potential solutions for low-cost photovoltaics and photonic sources in fields of solar cells, sensors, light-emitting diodes and lasers. Regardless of significant progress on device efficiency with the control over perovskite structures and film morphologies, unveiling the interface energetics and band alignment of these perovskite systems is indispensable for the performance optimization in the optoelectronic applications by grasping the photon harvest and charge transport processes. Herein we review the recent advances in the energetics of metal halide perovskite interfaces. The electronic properties of perovskite materials are addressed in terms of halide substitution, thermal annealing and substrate effects as well as trap states. The energy level alignments of interfaces between perovskite films and charge transport layers are then discussed, which is correlated to the photovoltaic properties in perovskite solar cells. [ABSTRACT FROM AUTHOR]

Perovskite-type LaFeO3 and α-Fe2O3 with high specific surface areas were directly prepared with appropriate stearic acid–nitrates ratios by a novel stearic acid solution combustion method. The obtained powders were characterized by XRD, FT-IR and XPS techniques. The catalytic activities of perovskite-type LaFeO3 and α-Fe2O3 for the thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) were investigated by TG and TG–EGA techniques. The experimental results show that the catalytic activity of perovskite-type LaFeO3 was much higher than that of α-Fe2O3 because of higher concentration of surface-adsorbed oxygen (Oad) and hydroxyl of LaFeO3. The study points out a potential way to develop new and more active perovskite-type catalysts for the HMX thermal decomposition. [Copyright &y& Elsevier]

Abstract: The paper discusses the Y and Nd doped barium cerate perovskites prepared by a modified Pechini method. The series prepared is described by the formula BaCe0.80Y x Nd0.2−x O3−δ . The BaCeO3 based powders, about 10–20 nm sized and uniformly shaped, were obtained through the calcination of the gel at 500 °C for 2 h. Their structures and ionic conductivities were characterized by X-ray diffraction and AC impedance spectroscopy. All the electrolytes were found to be barium cerate based solid solutions of perovskite type structures. Impedance spectra indicate that the grain boundary resistance of the specimen synthesized by this method is smaller than that of the samples prepared by a conventional solid-state method. The ionic conductivities of co-doped barium cerate were a factor of several times than that of the single-doped one at 673–1073 K. Among the electrolytes examined, the one co-doped with 5 mol% Nd and 15 mol% Y shows the best improvement in performance. These co-doped barium cerate are more ideal intermediate temperature (IT) electrolyte materials. [Copyright &y& Elsevier]

Deep-Blue Emission: Interfacial Potassium-Guided Grain Growth for Efficient Deep-Blue Perovskite Light-Emitting Diodes (Adv. Funct. Keywords: crystallization manipulation; deep-blue emission; interface engineering; perovskite light-emitting diodes EN crystallization manipulation deep-blue emission interface engineering perovskite light-emitting diodes 1 1 1 02/05/21 20210203 NES 210203 In article number 2006736, Yan-Qing Li, Jian-Xin Tang, and co-workers demonstrate a facile and reliable crystallization strategy for interfacial potassium-guided perovskite grain growth, leading to efficient deep-blue light-emitting diodes with an external quantum efficiency of 4.14% and stable color coordinates of (0.125, 0.076). Crystallization manipulation, deep-blue emission, interface engineering, perovskite light-emitting diodes. [Extracted from the article]

Hot carriers in hybrid perovskite have been proven to have eminent properties with long carrier cooling time and long carrier migration distance. The invention of the internally photoemitted hot carrier (IPHC) solar cell recently makes it possible to utilize the hot electrons in CH 3 NH 3 PbI 3 perovskite and capture their excess energies under steady state illumination. How to further improve the efficiency of IPHC cells is challenging and crucial to demonstrate their effectiveness. In this work, sodium iodide (NaI) is added into the CH 3 NH 3 PbI 3 precursor solution for inducing a P-type doping and downshifting its Fermi level. The lowered energy barrier at the interface of Au/doped CH 3 NH 3 PbI 3 promotes the hot electron extraction, thereby enhancing the power conversion efficiency of IPHC devices. The FTO/TiO 2 /Au/Na+-doped MAPbI 3 construction with considerable photocurrent would be an alternative approach for light-to-electricity conversion. Image 1 • A novel IPHC device has been adopted to collect hot electrons under steady-state sunlight illumination. • The location of the perovskite active layer is on the utmost outside of the collection structure of Au/TiO 2 /FTO. • The performance of this newly developed hot electron collection device is enhanced by P-type doping the perovskite layer. • P-type doping is the effective way to boost the hot electron internal photoemission. [ABSTRACT FROM AUTHOR]

Inorganic mixed‐halide CsPbX3‐based perovskite solar cells (PeSCs) are emerging as one of the most promising types of PeSCs on account of their thermostability compared to organic–inorganic hybrid counterparts. However, dissatisfactory device performance and high processing temperature impede their development for viable applications. Herein, a facile route is presented for tuning the energy levels and electrical properties of sol–gel‐derived ZnO electron transport material (ETM) via the doping of a classical alkali metal carbonate Cs2CO3. Compared to bare ZnO, Cs2CO3‐doped ZnO possesses more favorable interface energetics in contact with the CsPbI2Br perovskite layer, which can reduce the ohmic loss to a negligible level. The optimized PeSCs achieve an improved open‐circuit voltage of 1.28 V, together with an increase in fill factor and short‐circuit current. The optimized power conversion efficiencies of 16.42% and 14.82% are realized on rigid glass substrate and flexible plastic substrate, respectively. A high thermostability can be simultaneously obtained via defect passivation at the Cs2CO3‐doped ZnO/CsPbI2Br interface, and 81% of the initial efficiency is retained after aging for 200 h at 85 °C. [ABSTRACT FROM AUTHOR]

Flexible perovskite solar cells (PeSCs) possess the extraordinary potential in the applications of portable power sources and wearable electronics because of their superiorities in ease fabrication and efficient power conversion. These features are reinforced when a transparent conductive electrode with good flexibility is achieved. A unique electrode based on Ag periodic mesh (APM) perforated with hexagonal close‐packed nanoholes is proposed, showing a square resistance of ≈19.0 Ω sq−1 and optical transmittance of 66.0% in the whole visible region. PeSCs made on the optimal APM electrode with a rigid glass substrate achieve over twofold of photocurrent as compared to the counterpart on flat Ag film, resulting in a maximum power conversion efficiency of 17.06%. Experimental and theoretical characterizations indicate that the performance enhancement is mainly ascribed to the surface plasmon‐assisted extraordinary transmission enhancement and the scattering of incident light. Furthermore, the APM electrode enables PeSCs that are not only efficient but also highly flexible against bending deformation. Flexible PeSCs on plastic remain 90% of their initial efficiency after 1500 bending cycles with a bending radius of 3.0 mm. It is anticipated that the APM electrode with unique light coupling abilities provides a facile design route to achieving efficient and flexible PeSCs. [ABSTRACT FROM AUTHOR]

In article number 1801534, Yan‐Qing Li, Feng Gao, Chun‐Sing Lee, Jian‐Xin Tang, and co‐workers propose a method for the synergetic morphology control over cesium lead bromide perovskite films. Bright perovskite light‐emitting diodes (PeLEDs) are achieved due to the synergetic interplay of small grain sizes for efficient energy funneling and defect passivation for suppressing nonradiative recombination losses. Efficient flexible PeLEDs on plastics are also realized, showing great potential for commercially viable applications. [ABSTRACT FROM AUTHOR]

In article number 1801351, Jian‐Ming Yang, Qinye Bao, Jian‐Xin Tang and co‐workers review the recent progress on the interrelation between metal halide perovskites composition, electronic structure, and stability. The role of interface energetics and band alignment are summarized in terms of the charge extraction properties in perovskite solar cells. This review provides valuable reference in improving the device efficiency and durability through interface modification and addresses the precise control of electronic structures and degradation pathways, which possesses great potential toward efficient and stable perovskite‐based optoelectronic devices. [ABSTRACT FROM AUTHOR]

Metal halide perovskites are emerging as a new class of photoactive materials for next‐generation optoelectronics in recent years due to their unique optical and electronic properties. Regardless of significant progress on high‐performance perovskite‐based devices, it is of paramount importance to unveiling the interface energetics, which are crucial for the photon‐harvesting process and energy loss in the layered device configuration. In addition, the stability issue of perovskite materials and related devices has severely hindered their practical application. Herein, the recent advances in the interrelation between perovskite composition, electronic structure, and stability are reviewed. The interface energetics and band alignment with adjacent transport layers, as well as deterioration mechanisms, are addressed in terms of internal composition and external environmental factors. The strategies to improve the device efficiency and durability with interface modification are also discussed. The comprehensive microscopic understandings and precise control of electronic structures and degradation pathways exhibit great potential toward higher‐performance perovskite‐based optoelectronic devices. Recent progress in energetics and stability in metal halide perovskites and related interfaces are reviewed. Interface energetics and band alignment with adjacent transport layers, as well as deterioration mechanisms are addressed in terms of internal composition and external environmental factors. The strategies to improve device efficiency and durability with interface modification are also discussed. [ABSTRACT FROM AUTHOR]

An effective light trapping scheme in perovskite solar cells is achieved by incorporating bio‐inspired moth‐eye nanostructures into metal back electrode to improve the sunlight absorption. The enhanced light harvesting is ascribed by the collective effects of broadband polarization‐insensitive light scattering and surface plasmonic excitation. This is reported by Yan‐Qing Li, Chun‐Sing Lee, Jian‐Xin Tang, and co‐workers in article number 1700492. [ABSTRACT FROM AUTHOR]

Abstract While metal halide hybrid perovskite solar cells (PeSCs) are remarkably efficient, the rapid and undesirable degradation limit their practical applications for renewable energy sources. Herein, the evolution of perovskite decomposition under white light illumination has been investigated under the ultrahigh vacuum conditions, which can effectively rule out the influence of other factors such as oxygen or moisture. The chemical composition, electronic structure, surface morphology, and crystal structure of CH 3 NH 3 PbI 3 perovskite films have been systematically characterized by X-ray and ultraviolet photoelectron spectroscopies (XPS and UPS), scanning electron microscopy, and X-ray diffraction techniques. The surface roughening with cracks and defects occurs in CH 3 NH 3 PbI 3 perovskite films after a short-time white-light illumination in ultrahigh vacuum. In situ compositional analysis reveals the decomposition of the perovskite films with the appearance of metallic Pb feature, which is accompanied with the energy level shift towards higher binding energy during the illumination process. However, the decomposition rate is decreased and becomes saturated after exposed to light illumination for 24 h. These findings provide a direct evidence that CH 3 NH 3 PbI 3 perovskite is photosensitive, and a light-induced degradation mechanism is proposed. Graphical abstract Image 1 Highlights • The perovskite decomposition under white light illumination is explored under ultrahigh vacuum conditions. • In-situ compositional analysis reveals the perovskite decomposition with the appearance of metallic Pb. • A light-induced degradation mechanism is proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The DETA additive is used for domain regulation and radiative recombination. • The layer numbers of metal halide octahedron PbBr 6 4− can be precisely adjusted. • The emission of pure-bromide perovskites is tuned from violet to greenish-blue. • Efficient blue perovskite light-emitting diodes are achieved. • The EQEs are 1.74%, 2.44% and 5.71% for deep-, pure- and sky-blue emissions. Perovskite light-emitting diodes (PeLEDs) with green and red emissions have made tremendous progress in recent years. However, the realization of efficient and spectra-stable blue-emission PeLEDs remains challenging, which greatly limits their future commercialization. Here, a self-assembling strategy is proposed to achieve efficient blue PeLEDs with stable emission by modulating low-dimensional domains of pure-bromide perovskites to Bohr's radii. A spacer of butylamine with polyamine is used as a modifier to facilitate the formation of homogeneous perovskite films with precious tailoring of the numbers (N) of metal halide octahedron PbBr 6 4− layers. The cubic-phase quasi-2D perovskite films featuring the improved domain distributions and the enhanced luminance are realized, and their emissions can be modulated from violet (~436 nm) to greenish region (~500 nm), corresponding to the emission from N = 2 to N > 3 layered perovskites. The PeLEDs with deep-blue, pure-blue, and sky-blue emissions are obtained with the colour coordinates of (0.13, 0.06), (0.11, 0.13), and (0.08, 0.25), respectively, yielding the maximum external quantum efficiencies of 1.74%, 2.44%, and 5.71%. The approach demonstrated in this work paves the way for constructing efficient, endurable, spectra-stable perovskite emitters for the next-generation display and lighting technologies. [ABSTRACT FROM AUTHOR]

Perovskites light emitting diodes (PeLEDs) are promising candidates for next-generation display devices because of their attractive properties of low-cost, solution processability and excellent color purity. For metal halide perovskite materials, the emission tuning can be easily achieved by altering halide composition. However, blue PeLEDs with chlorine incorporation usually suffer from the severe phase segregation and ion migration, resulting in the red-shifted electroluminescence and the efficiency degradation. Here, the partial substitution of Pb2+ ions with non-toxic Sr2+ is adopted to enhance the formation energy of Sr-alloyed perovskite films, leading to the negligible electroluminescence in electrically driven blue PeLEDs. The maximum brightness and efficiency are optimized simultaneously. Further, such a substitution can greatly enhance the thermal and operational stabilities of PeLEDs. Image 1 • Nontoxic strontium was adopted to partly substitute Pb in perovskites for blue emission. • Spectral and thermal stabilities of PeLEDs are improved by inhibiting ion migrations. • The stability enhancement arises from the increase in the formation energy. [ABSTRACT FROM AUTHOR]