Surface Planarization-Epitaxial Growth Enables Uniform 2D/3D Heterojunctions for Efficient and Stable Perovskite Solar Modules.

Two-dimensional/three-dimensional (2D/3D) halide perovskite heterojunctions are widely used to improve the efficiency and stability of perovskite solar cells. However, interfacial defects between the 2D and 3D perovskites and the poor coverage of the 2D capping layer still hinder long-term stability and homogeneous charge extraction. Herein, a surface planarization strategy on 3D perovskite is developed that enables an epitaxial growth of uniform 2D/3D perovskite heterojunction via a vapor-assisted process.

Pathways of Water-Induced Lead-Halide Perovskite Surface Degradation: Insights from Atomic-Scale Analysis.

While organic-inorganic hybrid perovskites are emerging as promising materials for next-generation photovoltaic applications, the origins and pathways of perovskite instability remain speculative. In particular, the degradation of perovskite surfaces by ambient water is a crucial subject for determining the long-term viability of perovskite-based solar cells. Here, we conducted surface characterization and atomic-scale analysis of the reaction mechanisms for methylammonium lead bromide (MA(CHNH)PbBr) single crystals using ambient-pressure atomic force microscopy (AP-AFM) and near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) in environments ranging from ultrahigh vacuum to 0.

Recent Advances in Phosphorene: Structure, Synthesis, and Properties.

Phosphorene is a 2D phosphorus atomic layer arranged in a honeycomb lattice like graphene but with a buckled structure. Since its exfoliation from black phosphorus in 2014, phosphorene has attracted tremendous research interest both in terms of synthesis and fundamental research, as well as in potential applications. Recently, significant attention in phosphorene is motivated not only by research on its fundamental physical properties as a novel 2D semiconductor material, such as tunable bandgap, strong in-plane anisotropy, and high carrier mobility, but also by the study of its wide range of potential applications, such as electronic, optoelectronic, and spintronic devices, energy conversion and storage devices.

Local Built-In Field at the Sub-nanometric Heterointerface Mediates Cascade Electrochemical Conversion of Lithium-sulfur Batteries.

Heterogeneous catalytic mediators have been proposed to play a vital role in enhancing the multiorder reaction and nucleation kinetics in multielectron sulfur electrochemistry. However, the predictive design of heterogeneous catalysts is still challenging, owing to the lack of in-depth understanding of interfacial electronic states and electron transfer on cascade reaction in Li-S batteries. Here, a heterogeneous catalytic mediator based on monodispersed titanium carbide sub-nanoclusters embedded in titanium dioxide nanobelts is reported.

Graphene-Like Conjugated Molecule as Hole-Selective Contact for Operationally Stable Inverted Perovskite Solar Cells and Modules.

Further enhancing the operational lifetime of inverted-structure perovskite solar cells (PSCs) is crucial for their commercialization, and the design of hole-selective contacts at the illumination side plays a key role in operational stability. In this work, the self-anchoring benzo[rst]pentaphene (SA-BPP) is developed as a new type of hole-selective contact toward long-term operationally stable inverted PSCs. The SA-BPP molecule with a graphene-like conjugated structure shows a higher photostability and mobility than that of the frequently-used triphenylamine and carbazole-based hole-selective molecules.

Heterogeneous FASnI Absorber with Enhanced Electric Field for High-Performance Lead-Free Perovskite Solar Cells.

Lead-free tin perovskite solar cells (PSCs) have undergone rapid development in recent years and are regarded as a promising eco-friendly photovoltaic technology. However, a strategy to suppress charge recombination via a built-in electric field inside a tin perovskite crystal is still lacking. In the present study, a formamidinium tin iodide (FASnI) perovskite absorber with a vertical Sn gradient was fabricated using a Lewis base-assisted recrystallization method to enhance the built-in electric field and minimize the bulk recombination loss inside the tin perovskites.

Spectral Stable Blue-Light-Emitting Diodes via Asymmetric Organic Diamine Based Dion-Jacobson Perovskites.

The spectral instability issue is a challenge in blue perovskite light-emitting diodes (PeLEDs). Dion-Jacobson (DJ) phase perovskites are promising alternatives to achieve high-quality blue PeLEDs. However, the current exploration of DJ phase perovskites is focused on symmetric divalent cations, and the corresponding efficiency of blue PeLEDs is still inferior to that of green and red ones.

Atomic Level Insights into Metal Halide Perovskite Materials by Scanning Tunneling Microscopy and Spectroscopy.

Metal halide perovskite materials (MHPMs) have attracted significant attention because of their superior optoelectronic properties and versatile applications. The power conversion efficiency of MHPM solar cells (PSCs) has skyrocketed to 25.5 %.

Atomic Scale Investigation of the CuPc-MAPbX Interface and the Effect of Non-Stoichiometric Perovskite Films on Interfacial Structures.

Metal halide perovskites (MHPs) have become a major topic of research in thin film photovoltaics due to their advantageous optoelectronic properties. These devices typically have the MHP absorber layer sandwiched between two charge selective layers (CSLs). The interfaces between the perovskite layer and these CSLs are potential areas of higher charge recombination.

Long-life lithium-sulfur batteries with high areal capacity based on coaxial CNTs@TiN-TiO sponge.

Rational design of heterostructures opens up new opportunities as an ideal catalyst system for lithium polysulfides conversion in lithium-sulfur battery. However, its traditional fabrication process is complex, which makes it difficult to reasonably control the content and distribution of each component. In this work, to rationally design the heterostructure, the atomic layer deposition is utilized to hybridize the TiO-TiN heterostructure with the three-dimensional carbon nanotube sponge.

Up-Scalable Fabrication of SnO with Multifunctional Interface for High Performance Perovskite Solar Modules.

Tin dioxide (SnO) has been demonstrated as one of the promising electron transport layers for high-efficiency perovskite solar cells (PSCs). However, scalable fabrication of SnO films with uniform coverage, desirable thickness and a low defect density in perovskite solar modules (PSMs) is still challenging. Here, we report preparation of high-quality large-area SnO films by chemical bath deposition (CBD) with the addition of KMnO.

Lead halide-templated crystallization of methylamine-free perovskite for efficient photovoltaic modules.

Upscaling efficient and stable perovskite layers is one of the most challenging issues in the commercialization of perovskite solar cells. Here, a lead halide-templated crystallization strategy is developed for printing formamidinium (FA)-cesium (Cs) lead triiodide perovskite films. High-quality large-area films are achieved through controlled nucleation and growth of a lead halide•-methyl-2-pyrrolidone adduct that can react in situ with embedded FAI/CsI to directly form α-phase perovskite, sidestepping the phase transformation from δ-phase.

Slot-die coating large-area formamidinium-cesium perovskite film for efficient and stable parallel solar module.

Perovskite solar cells have emerged as one of the most promising thin-film photovoltaic (PV) technologies and have made a strong debut in the PV field. However, they still face difficulties with up-scaling to module-level devices and long-term stability issue. Here, we report the use of a room-temperature nonvolatile Lewis base additive, diphenyl sulfoxide(DPSO), in formamidinium-cesium (FACs) perovskite precursor solution to enhance the nucleation barrier and stabilize the wet precursor film for the scalable fabrication of uniform, large-area FACs perovskite films.

Comparison of Thermal Annealing Hydrothermal Treatment Effects on the Detection Performances of ZnO Nanowires.

A comparative investigation of the post-electroplating treatment influence on the gas detecting performances of single ZnO nanorod/nanowire (NR/NW), as grown by electrochemical deposition (ECD) and integrated into nanosensor devices, is presented. In this work, hydrothermal treatment (HT) in a HO steam and conventional thermal annealing (CTA) in a furnace at 150 °C in ambient were used as post-growth treatments to improve the material properties. Herein, the morphological, optical, chemical, structural, vibrational, and gas sensing performances of the as-electrodeposited and treated specimens are investigated and presented in detail.

Inverse Growth of Large-Grain-Size and Stable Inorganic Perovskite Micronanowire Photodetectors.

Control of forward and inverse reactions between perovskites and precursor materials is key to attaining high-quality perovskite materials. Many techniques focus on synthesizing nanostructured CsPbX materials (e.g.

Imaging of the Atomic Structure of All-Inorganic Halide Perovskites.

All-inorganic halide perovskites are promising materials for optoelectronic applications. The surface or interface structure of the perovskites plays a crucial role in determining the optoelectronic conversion efficiency, as well as the material stability. A thorough understanding of surface atomic structures of the inorganic perovskites and their contributions to their optoelectronic properties and stability is lacking.

Surface Defect Dynamics in Organic-Inorganic Hybrid Perovskites: From Mechanism to Interfacial Properties.

Organic-inorganic hybrid perovskites (OHPs) have garnered much attention among the photovoltaic and light-emitting diode research community due to their excellent optoelectronic properties and low-cost fabrication. Defects in perovskites have been proposed to affect device efficiency and stability and to have a potential role in enabling ion migration. In this study, the dynamic behavior and electronic properties of intrinsic defects in CHNHPbBr (MAPbBr) were explored at the atomic scale.

Thermodynamically stabilized β-CsPbI-based perovskite solar cells with efficiencies >18.

Although β-CsPbI has a bandgap favorable for application in tandem solar cells, depositing and stabilizing β-CsPbI experimentally has remained a challenge. We obtained highly crystalline β-CsPbI films with an extended spectral response and enhanced phase stability. Synchrotron-based x-ray scattering revealed the presence of highly oriented β-CsPbI grains, and sensitive elemental analyses-including inductively coupled plasma mass spectrometry and time-of-flight secondary ion mass spectrometry-confirmed their all-inorganic composition.

Reducing Detrimental Defects for High-Performance Metal Halide Perovskite Solar Cells.

In several photovoltaic (PV) technologies, the presence of electronic defects within the semiconductor band gap limit the efficiency, reproducibility, as well as lifetime. Metal halide perovskites (MHPs) have drawn great attention because of their excellent photovoltaic properties that can be achieved even without a very strict film-growth control processing. Much has been done theoretically in describing the different point defects in MHPs.

Degradation Mechanism and Relative Stability of Methylammonium Halide Based Perovskites Analyzed on the Basis of Acid-Base Theory.

The correct identification of all gases released during hybrid perovskite degradation is of great significance to develop strategies to extend the lifespan of any device based on this semiconductor. CHX (X = Br/I) is a released degradation gas/low boiling point liquid arising from methylammonium (MA) based perovskites, which has been largely overlooked in the literature focusing on stability of perovskite solar cells. Herein, we present an unambiguous identification of CHI release using microwave (rotational) spectroscopy.

Highly Efficient and Stable Perovskite Solar Cells via Modification of Energy Levels at the Perovskite/Carbon Electrode Interface.

Perovskite solar cells (PSCs) have attracted great attention in the past few years due to their rapid increase in efficiency and low-cost fabrication. However, instability against thermal stress and humidity is a big issue hindering their commercialization and practical applications. Here, by combining thermally stable formamidinium-cesium-based perovskite and a moisture-resistant carbon electrode, successful fabrication of stable PSCs is reported, which maintain on average 77% of the initial value after being aged for 192 h under conditions of 85 °C and 85% relative humidity (the "double 85" aging condition) without encapsulation.

Unraveling the Impact of Halide Mixing on Perovskite Stability.

Increasing the stability of perovskites is essential for their integration in commercial photovoltaic devices. Halide mixing is suggested as a powerful strategy toward stable perovskite materials. However, the stabilizing effect of the halides critically depends on their distribution in the mixed compound, a topic that is currently under intense debate.

Highly stable and efficient all-inorganic lead-free perovskite solar cells with native-oxide passivation.

There has been an urgent need to eliminate toxic lead from the prevailing halide perovskite solar cells (PSCs), but the current lead-free PSCs are still plagued with the critical issues of low efficiency and poor stability. This is primarily due to their inadequate photovoltaic properties and chemical stability. Herein we demonstrate the use of the lead-free, all-inorganic cesium tin-germanium triiodide (CsSnGeI) solid-solution perovskite as the light absorber in PSCs, delivering promising efficiency of up to 7.