Colloidal quantum dots (QDs) of lead halide perovskite have recently received great attention owing to their remarkable performances in optoelectronic applications. However, their wide applications are hindered from toxic lead element, which is not environment- and consumer-friendly. Herein, we utilized heterovalent substitution of divalent lead (Pb) with trivalent antimony (Sb) to synthesize stable and brightly luminescent CsSbBr QDs. The lead-free, full-inorganic QDs were fabricated by a modified ligand-assisted reprecipitation strategy. A photoluminescence quantum yield (PLQY) was determined to be 46% at 410 nm, which was superior to that of other reported halide perovskite QDs. The PL enhancement mechanism was unraveled by surface composition derived quantum-well band structure and their large exciton binding energy. The Br-rich surface and the observed 530 meV exciton binding energy were proposed to guarantee the efficient radiative recombination. In addition, we can also tune the inorganic perovskite QD (CsSbX) emission wavelength from 370 to 560 nm via anion exchange reactions. The developed full-inorganic lead-free Sb-perovskite QDs with high PLQY and stable emission promise great potential for efficient emission candidates.

sensitivity are the bottlenecks in future commercialization applications. [4,5] Fully-inorganic lead halide perovskites (APbX 3 , A = Cs, Rb, K, etc.), without the organic part affection were expected to resolve the problem of stability. [4,6,7] According to the work of Kubelk et al., fullyinorganic perovskites have similar bandgaps to organo-lead halide analogs and hold much better thermal stability. [4,[7][8][9] Under the scenario of lead-free perovskite, tin (Sn) and germanium (Ge) elements have been considered as hot candidates [10] to replace lead. However, the quick oxidation from Sn 2+ /Ge 2+ to Sn 4+ /Ge 4+ greatly degrades their PCE. [11][12][13] To overcome this problem, heterovalent elements of Sb and Bi were introduced for the implementation of green perovskite. And these perovskite molecular structures transmute from ABX 3 to their derivatives such as A 3 B 2 X 9 .For antimony iodide perovskite (AIP) [14,15] research work, Mitzi and our group combined theoretical calculations, film deposition, and experimental characterizations to understand this new absorber semiconductor. Two kinds of polymorphs exist for Cs 3 Sb 2 I 9 , 0D (dimer) and 2D (layered) phases. Dimer phase exhibits indirect bandgap of 2.50 eV unfavorable for photo voltaics, while layered phase has a direct bandgap of 2.05 eV, a suitable choice as active absorber. The latter one provides similar high level of absorption as CH 3 NH 2 PbI 3 and relatively small in-plane and out-of-plane effective mass. [16][17][18] The layered film could only be synthesized by vapor method with annealing temperature ≈300 °C under the assistance of SbI 3 vapor. [16] Utilizing similar SbI 3 vapor reaction with CsI and SbI 3 precursor film, Chu and co-workers obtained AIP-layered thin film solar cells via a structure of ITO/PEDOT:PSS/AIP/ PC 70 BM/Al and obtained a PCE value of 1.49%. [19] In addition to unique optoelectronic properties, LIP solar cells obtained huge progress highly relying on convenient solution method. The present layered AIP vapor method required high reaction temperature as well as nonuniform composition. Thus, we tried to develop a simple solution method for layered AIP absorbers. According to Zhou and co-workers' theoretical calculations, the AIP dimer phase is an energetically stable Since lead halide perovskite suffers from the obstructions of lead and stability, researchers recently pay more attention to the development of lead-free and stable perovskite absorbers. A typical lead-free antimony iodide perovskite (AIP) is synthesized through vapor reaction at high temperature for photoactive phase. Herein, hydrochloric acid is developed as an intermediate coordinated additive for Cs 3 Sb 2 I 9 photoactive layered phase using HCl-assisted solution method. The uniform and highly crystalline Cs 3 Sb 2 I 9 layered film is obtained by antisolvent engineering. Isopropanol antisolvent is more suitable for present system comparing with traditional lead iodide perovskite-based ones. Physical characterizations manifest the lower trap density, do...

Antimony sulfide (Sb2S3) as a wide‐bandgap, nontoxic, and stable photovoltaic material reveals great potential for the uppermost cells in Si‐based tandem cell stacks. Sb2S3 solar cells with a compatible process, acceptable cost, and high efficiency therefore become the mandatory prerequisites to match silicon bottom cells. The performance of vacuum processed Sb2S3 device is pinned by bulk and interfacial recombination. Herein, a thermally treated TiO2 buffer layer induces quasiepitaxial growth of vertical orientation Sb2S3 absorber overcoming interface defects and absorber transport loss. Such novel growth could pronouncedly improve the open‐circuit voltage (Voc) due to the superior interface quality and intraribbon transport. The epitaxial rough Sb2S3 surface shows a texturized‐like morphology. It is optimized by tuning the grain sizes to form strong light trapping effect, which further enhances the short‐circuit current density (Jsc) with a 16% improvement. The final optimal device with high stability obtains a power conversion efficiency of 5.4%, which is the best efficiency for full‐inorganic Sb2S3 solar cells. The present developed quasiepitaxy strategy supports a superior interface, vertical orientation, and surface light trapping effect, which provides a new perspective for efficient noncubic material thin film solar cells.

Metal halide perovskites are crystalline materials originally developed out of scientific curiosity. They have shown great potential as active materials in optoelectronic applications. In the last 6 years, their certified photovoltaic efficiencies have reached 22.1%. Compared to bulk halide perovskites, low-dimensional ones exhibited novel physical properties. The photoluminescence quantum yields of perovskite quantum dots are close to 100%. The external quantum efficiencies and current efficiencies of perovskite quantum dot light-emitting diodes have reached 8% and 43 cd A−1, respectively, and their nanowire lasers show ultralow-threshold room-temperature lasing with emission tunability and ease of synthesis. Perovskite nanowire photodetectors reached a responsivity of 10 A W−1 and a specific normalized detectivity of the order of 1012 Jones. Different from most reported reviews focusing on photovoltaic applications, we summarize the rapid progress in the study of low-dimensional perovskite materials, as well as their promising applications in optoelectronic devices. In particular, we review the wide tunability of fabrication methods and the state-of-the-art research outputs of low-dimensional perovskite optoelectronic devices. Finally, the anticipated challenges and potential for this exciting research are proposed.

The recent emerging progress of quantum dot ink (QD-ink) has overcome the complexity of multiple-step colloidal QD (CQD) film preparation and pronouncedly promoted the device performance. However, the detrimental hydroxyl (OH) ligands induced from synthesis procedure have not been completely removed. Here, a halide ligand additive strategy was devised to optimize QD-ink process. It simultaneously reduced sub-bandgap states and converted them into iodide-passivated surface, which increase carrier mobility of the QDs films and achieve thicker absorber with improved performances. The corresponding power conversion efficiency of this optimized device reached 10.78%. (The control device was 9.56%.) Therefore, this stratege can support as a candidate strategy to solve the QD original limitation caused by hydroxyl ligands, which is also compatible with other CQD-based optoelectronic devices.

Development of cost effective and efficient electrocatalysts is crucial to generate H2 as an alternative source of energy. However, expensive noble metal based electrocatalysts show best electrocatalytic performances which acts as main bottle-neck for commercial application. Therefore, non-precious electrocatalysts have become important for hydrogen and oxygen evolution reactions. Herein, we report the synthesis of high surface area (35 m2/g) sodium niobate nanoparticles by citrate precursor method. These nanoparticles were characterized by different techniques like X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. Electrocatalytic properties of cost-effective sodium niobate nanoparticles were investigated for HER and OER in 0.5 M KOH electrolyte using Ag/AgCl as reference electrode. The sodium niobate electrode showed significant current density for both OER (≈2.7 mA/cm2) and HER (≈0.7 mA/cm2) with onset potential of 0.9 V for OER and 0.6 V for HER. As-prepared sodium niobate nanoparticles show enhanced photocatalytic property (86% removal) towards the degradation of rose Bengal dye. Dielectric behaviour at different sintering temperatures was explained by Koop’s theory and Maxwell-Wagner mechanism. The dielectric constants of 41 and 38.5 and the dielectric losses of 0.04 and 0.025 were observed for the samples sintered at 500 °C and 700 °C, respectively at 500 kHz. Conductivity of the samples was understood by using power law fit.

Sb2(SexS1–x)3 has been proven a very promising light absorbing material for photovoltaic applications due to its high stability, tunable band gap, non‐toxic element, and high extinction coefficient. For Sb2(SexS1–x)3 alloy film deposition, the authors develop a single source based rapid‐thermal‐evaporation (RTE) method instead of the traditional in‐situ sulfurization or double source co‐evaporation based RTE method. The absorber band gap can be precisely tuned from 1.1 to 1.7 eV by simply varying the molar ratio of Sb2Se3 and Sb2S3 source powder. From the systematical composition screening, FTO/CdS/Sb2(Se0.68S0.32)3/Au devices show higher power conversion efficiency (PCE ∼ 4.17%) when compared with other absorber compositions based devices. In order to achieve thinner ETL layers and simultaneously avoid pinholes led by rough FTO surface, we introduce for the first time double buffer layer in the Sb2(Se0.68S0.32)3 device system which could further improve the device efficiency from 4.17% to 5.73%. The double buffer layer ZnO/CdS helped to form graded energy band alignment, suppress charge recombination and efficiently extract electrons. The devices obtained higher Jsc and Voc supported by various physical characterization analyses. The facile single source deposition method, efficient double buffer layer device structure and notable PCE are expected to pronouncedly promote antimony chalcogenide device development.

Population explosion has caused serious environmental and energy-related problems that have increased the interest of researchers to develop new nontoxic, inexpensive, stable, and efficient materials to address these environment and energy-related issues. Among the different efforts, the development of photocatalysts is considered as an important way to utilize the sustainable solar energy for environment remediation and energy purposes. Presently, several hundred photocatalysts have been synthesized. Among them, alkali niobates and tantalates represent an important class of photocatalysts, because of their nontoxicity, structural flexibility, and simplicity. This review summarizes recent developments in synthetic strategies of alkali niobate and tantalates, their important application as photocatalysts for environment remediation and energy applications, and efforts being made to modify their physicochemical properties and extend their efficiencies by tuning different reaction conditions. The purpose of this Review is to discuss methods to regulate the efficiencies of these materials and future challenges faced for practical applications.