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Antisolvent assisted crystallization has been most widely applied in depositing high-quality perovskite thin films for efficient perovskite solar cells (PSCs). However, the toxicity of common antisolvents (chlorobenzene, toluene etc.) involved in perovskite processing raises serious environmental and health concerns for large-scale implementation. Herein, a green co-antisolvent of propyl acetate is induced to adjust the degree of supersaturation in diethyl ether, enabling pinhole-free, smooth, and uniform perovskite thin films. By carefully controlling the polarity of the antisolvents, the deposited perovskite film showed higher electron mobility and suppressed defect density than that of the control film. As a result, a high power conversion efficiency up to 20.61% was achieved in a p–i–n inverted MAPbI3 PSC with an impressive fill factor (FF) over 84%. The high FF is mainly attributed to the attenuated ideal factor and improved diode junction quality. This approach provides a greener path to the sustainability and scalability of the emerging PSC technology. [ABSTRACT FROM AUTHOR]

Defects, inevitably produced in solution-processed halide perovskite films, can act as charge carrier recombination centers to induce severe energy loss in perovskite solar cells (PSCs). Suppressing these trap states has been regarded as one of the effective strategies to improve the photovoltaic performance and stability of PSCs. Herein, a small molecule of 3-picolinic acid, a commodity chemical with a carboxyl group (–COOH) better known by its common name niacin, which can be chemically anchored to methylammonium lead iodide (MAPbI3) through the coordination effect, is introduced to passivate the defects and control the perovskite crystal growth. Highly crystalline perovskite films with a large grain size are obtained. The passivation within the perovskite via the interaction of –COOH in niacin with Pb2+ is verified by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, as well as density functional theory calculations. Consequently, the device with niacin achieved a power conversion efficiency close to 20%, along with much more enhanced air and ultraviolet illumination stability, compared to the control device. [ABSTRACT FROM AUTHOR]

Carrier transport layers have been recognized as a key factor to determine the performance of perovskite solar cells (PSCs) by dominating the charge carrier extraction, transport and recombination process. Metal oxides have been widely used as electron transport layers (ETLs) in PSCs for high performance and stability, of which TiO2 and SnO2 are the most popular choices. However, the large-scale implementation of TiO2 and SnO2 ETLs is hindered by their own deficiencies, such as low electron mobility, poor stability against UV light and surface defects. Therefore, binary and ternary metal oxide alternatives have been widely investigated recently. Here, we review the recent advances of these metal oxide ETLs in PSCs with a special focus on the nanostructuring, elemental doping, surface modification, and multi-layer ETLs and large-scale fabrication of these ETLs. Furthermore, the state-of-the-art progress towards high-efficiency and stable PSCs using these novel ETLs is summarized and future perspectives are discussed. [ABSTRACT FROM AUTHOR]

The development of low-dimensional non-precious metal catalysts for the hydrogen evolution reaction (HER) is highly desired for clean energy utilization. Herein, we have reported a facile synthesis protocol of Cu–Mo–O (CMO) nanowires and nanosheets on Cu foam (CMOW/CF and CMOS/CF) through a one-step reaction of Cu nanowires with (NH4)6Mo7O24 solution directly under mild conditions. The final product morphology has been tuned by mechanical stirring. The as-synthesized CMOS/CF exhibits a low operating overpotential of 112 mV at a current density of 10 mA cm−2 with a high electrochemical active area of 25.1 mF cm−2 and excellent long-term stability in the 1 M KOH electrolyte. Moreover, by using the CMOS/CF as cathodic and anodic electocatalysts, a two-electrode electrolyzer capable of driving 10 mA cm−2 at a cell voltage of 1.69 V was achieved, along with promising stability. The high performance of the CMOS/CF can be attributed to higher electrochemical area and more Mo catalytic sites induced by mechanical stirring. This work provides a facile method for the synthesis and catalytic site regulation through a simple method of low-dimensional nanomaterials for the HER with relatively high electrochemical active area and catalytic activity. [ABSTRACT FROM AUTHOR]

Halide perovskite solar cells (PSCs) have been materialized as a hotspot in the next-generation photovoltaic technology due to their low-cost manufacturing process and high-efficiency characteristics. However, the defects within the bulk or in the grain boundaries and surface hinder ambipolar charge transport as non-radiative recombination centers. Efficacious defect passivation is therefore highly desired for high-efficiency and stable PSCs. Herein, a feasible Lewis acid/base passivation strategy and its effects on energy level alignment, recombination kinetics, hysteresis behavior and operational stability for efficient PSCs are comprehensively reviewed. These additives have been widely used to coordinate with unwanted defects and form Lewis adducts by dative bonds, where the Lewis acid contributes to passivate negatively charged defects (e.g., under-coordinated I− ions and Pb–I anti-sites) and the Lewis base plays a significant role in passivating positively charged defects (e.g., under-coordinated Pb2+ and Pb2+ interstitials), whereas zwitterions could passivate negatively and positively charged defects simultaneously. This highly executable Lewis adduct passivation would enable scalable deposition techniques for efficient and stable PSCs like inkjet printing, doctor-blade coating, screen printing, laser pattering and roll-to-roll deposition. Additionally, we also discuss the prospects of the maturity of this passivation strategy towards upscaling manufacture of perovskite photovoltaic and related optoelectronic devices. [ABSTRACT FROM AUTHOR]

Industrially, artificial N2 fixation to NH3 mainly relies on the Haber–Bosch process which is operated in a harsh environment with large energy consumption and heavy serious greenhouse gas emission. Electrochemical N2 reduction offers a carbon-neutral and energy-saving method for NH3 synthesis under ambient conditions. Herein, we demonstrate the first use of ZrO2 nanoparticles as an earth-abundant electrocatalyst for NH3 synthesis from N2 and water under ambient conditions. In 0.1 M HCl, the electrocatalyst presents a large NH3 yield rate of 24.74 μg h−1 mgcat.−1 with a faradaic efficiency of 5.0% at −0.45 V vs. the reversible hydrogen electrode. It also demonstrates high electrochemical stability and excellent selectivity for NH3 generation. [ABSTRACT FROM AUTHOR]

The morphology and optoelectronic properties of perovskite films are the key to high-performance perovskite solar cells (PSCs). Here, a facile non-destructive interface ethanol/chlorobenzene (EtOH/CB) post treatment was established for the lateral grain growth of MAPbI3 perovskite films and fabrication of efficient solar cells. The alcoholic treatment leads to perovskite grain coarsening and a secondary growth in the average grain size from 38.88 μm to 89.59 μm. The enlargement of the perovskite crystals induced a notable defect passivation and attenuated charge recombination centers as confirmed by photoluminescence, electrochemical impedance spectroscopy, and photocharge extraction by a linearly-increasing voltage. Accordingly, inverted planar PSC devices showed an 18% enhancement in the overall power conversion efficiency using this alcoholic post-treatment under ambient fabrication conditions. Our results demonstrate a versatile strategy for the lateral growth of perovskite photovoltaics and beyond. [ABSTRACT FROM AUTHOR]

The artificial N2 fixation to NH3 is dominated by the traditional Haber–Bosch process, which consumes large amounts of energy and natural gas with low energy efficiency and large amounts of CO2 emissions. Electrochemical N2 reduction is a promising and environmentally friendly route for artificial N2-to-NH3 fixation under milder conditions. Herein, we report that dendritic Cu acts as a highly active electrocatalyst to catalyze N2 to NH3 fixation under ambient conditions. When tested in 0.1 M HCl, such an electrocatalyst achieves a high faradaic efficiency of 15.12% and a large NH3 yield rate of 25.63 μg h−1 mgcat.−1 at −0.40 V versus a reversible hydrogen electrode. Notably, this catalyst shows high electrochemical stability and excellent selectivity toward NH3 synthesis. [ABSTRACT FROM AUTHOR]

Metal halide perovskite materials have drawn worldwide attention for application in a variety of optoelectronic devices, especially in the emerging photovoltaic devices. In recent years, remarkable progress has been achieved in the device performance and stability. The optoelectronic properties of metal halide perovskites can be further tuned by ion doping. Herein, a comprehensive review of the incorporation of alkali metal ions (Li+, Na+, K+ and Rb+) in emerging perovskite solar cells for a longer carrier lifetime, lower interfacial defect density, faster charge transfer, no hysteresis, higher stability and higher power conversion efficiency is presented. The detailed mechanism behind these beneficial effects has been discussed in terms of electronic properties, film morphology, energy level alignment, carrier recombination dynamics and stability. On the basis of these latest advances and breakthroughs in alkali ion doped perovskite thin films, future research directions and prospects are also discussed, which include further understanding of the underlying photophysical mechanism and extension to other optoelectronic devices where a longer carrier lifetime and lower trap density are needed. [ABSTRACT FROM AUTHOR]

Most of the electron transport layers (ETLs) used in inverted perovskite solar cells (PSCs) are fullerene derivatives, which are relatively expensive due to the complex synthesis process. Here we report coenzyme Q10, composed of quinone as the acceptor group and an alkyl chain as the donor group, which can be used as a low cost ETL alternative in inverted PSCs. The energy level alignments, carrier transport and recombination dynamics were systematically studied in comparison with the benchmark PC61BM. By optimizing the device structure and thickness of the ETL, the device with Q10 exhibits a comparable power conversion efficiency to the PC61BM device under the standard irradiation conditions. The carrier transport and recombination processes were further evaluated through steady state and time-resolved photoluminescence spectroscopy, space-charge-limited current, and Mott–Schottky measurements. An accelerated carrier injection ability and a passivated interface defect density between the perovskite and Q10 ETL were observed. Charge density difference from DFT calculations also determined that the band alignment of Q10 promoted easier charge transport from the perovskite. Moreover, the long alkyl chain of the Q10 molecule endows it with excellent hydrophobic properties, which largely improves the water-resistance capability of the Q10 ETL. This work highlights the great potential of Q10 as a cheap alternative for the most popular PC61BM ETL for inverted PSCs. [ABSTRACT FROM AUTHOR]

As a carbon-neutral alternative to the Haber–Bosch process, electrochemical N2 reduction enables environment-friendly NH3 synthesis under ambient conditions but needs active electrocatalysts for the N2 reduction reaction (NRR). In this communication, we report on the first experimental demonstration that non-metal boron phosphide (BP) nanoparticles can be used as a high-efficiency catalyst for the ambient electrohydrogenation of N2 to NH3 with excellent selectivity. In 0.1 M HCl, this catalyst offers a high NH3 yield of 26.42 μg h−1 mgcat.−1 and a high faradaic efficiency of 12.7% at −0.60 V vs. the reversible hydrogen electrode, much superior to those of reported B catalysts. Such an enhancement is attributed to the fact that P in BP further weakens the N≡N bond while simultaneously strengthening the B–N bond and favors the exposure of more active sites for the NRR catalysis, which is supported by density functional theory calculations. [ABSTRACT FROM AUTHOR]

The synthesis of NH3 heavily relies on the Haber–Bosch process suffering from a large amount of CO2 emission and energy consumption. Possessing eco-friendly and sustainable characteristics, electrochemical reduction is considered as a promising candidate for artificial N2 fixation under ambient conditions, but efficient electrocatalysts are crucial for the N2 reduction reaction (NRR). In this communication, we report that perovskite La2Ti2O7 nanosheets behave as an efficient NRR electrocatalyst with excellent selectivity under ambient conditions. In 0.1 M HCl, this catalyst achieves a high NH3 yield rate of 25.15 μg h−1 mgcat.−1 with a faradaic efficiency of 4.55% at −0.55 V vs. a reversible hydrogen electrode. Notably, it also shows high electrochemical stability. [ABSTRACT FROM AUTHOR]

Industrially, artifical N 2 fixation to NH 3 mainly relies on the Haber-Bosch process which is operated in a harsh environment with large energy consumption and heavy serious greenhouse gas emission. Electrochemical N 2 reduction offers a carbon-neutral and energy-saving method for NH 3 synthesis under ambient conditions. Herein, we demonstrate the first use of ZrO 2 nanoparticles as an earth-abundant electrocatalyst for NH 3 synthesis from N 2 and water under ambient conditions. In 0.1 M HCl, the electrocatalyst presents a large NH 3 yield rate of 24.74 μg h -1 mg cat. -1 with a faradaic efficiency of 5.0% at -0.45 V vs. the reversible hydrogen electrode. It also demonstrates high electrochemical stability and excellent selectivity for NH 3 generation.

The artificial N2 fixation to NH3 is dominated by the traditional Haber-Bosch process, which consumes large amounts of energy and natural gas with low energy efficiency and large amounts of CO2 emissions. Electrochemical N2 reduction is a promising and environmentally friendly route for artificial N2-to-NH3 fixation under milder conditions. Herein, we report that dendritic Cu acts as a highly active electrocatalyst to catalyze N2 to NH3 fixation under ambient conditions. When tested in 0.1 M HCl, such an electrocatalyst achieves a high faradaic efficiency of 15.12% and a large NH3 yield rate of 25.63 μg h-1 mgcat.-1 at -0.40 V versus a reversible hydrogen electrode. Notably, this catalyst shows high electrochemical stability and excellent selectivity toward NH3 synthesis.

The synthesis of NH3 heavily relies on the Haber-Bosch process suffering from a large amount of CO2 emission and energy consumption. Possessing eco-friendly and sustainable characteristics, electrochemical reduction is considered as a promising candidate for artificial N2 fixation under ambient conditions, but efficient electrocatalysts are crucial for the N2 reduction reaction (NRR). In this communication, we report that perovskite La2Ti2O7 nanosheets behave as an efficient NRR electrocatalyst with excellent selectivity under ambient conditions. In 0.1 M HCl, this catalyst achieves a high NH3 yield rate of 25.15 μg h-1 mgcat.-1 with a faradaic efficiency of 4.55% at -0.55 V vs. a reversible hydrogen electrode. Notably, it also shows high electrochemical stability.