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A surface disordered layer is a plausible approach to improve the photoelectrochemical performance of TiO2. However, the formation of a crystalline disordered layer in BiVO4 and its effectiveness towards photoelectrochemical water splitting has remained a big challenge. Here, we report a rapid solution process (within 5 s) that is able to form a disordered layer of a few nanometers thick on the surface of BiVO4 nanoparticles using a specific solution with a controllable reducing power. The disordered layer on BiVO4 alleviates charge recombination at the electrode–electrolyte interface and reduces the onset potential greatly, which in turn results in a photocurrent density of approximately 2.3 mA cm−2 at 1.23 V versus the reversible hydrogen electrode (RHE). This value is 2.1 times higher than that of bare BiVO4. The enhanced photoactivity is attributed to the increased charge separation and transfer efficiencies, which resolve the intrinsic drawbacks of bare BiVO4 such as the short hole diffusion length of around 100 nm and poor surface oxygen evolution reactivity. [ABSTRACT FROM AUTHOR]

To further increase the open‐circuit voltage (Voc) of perovskite solar cells (PSCs), many efforts have been devoted to doping the TiO2 electron transport/selective layers by using metal dopants with higher electronegativity than Ti. However, those dopants can introduce undesired charge traps that hinder charge transport through TiO2, so the improvement in the Voc is often accompanied by an undesired photocurrent density–voltage (J–V) hysteresis problem. Herein, it is demonstrated that the use of a rapid flame doping process (40 s) to introduce cobalt dopant into TiO2 not only solves the J–V hysteresis problem but also increases the Voc and power conversion efficiency of both mesoscopic and planar PSCs. The reasons for the simultaneous improvements are two fold. First, the flame‐doped Co‐TiO2 film forms Co‐Ov (cobalt dopant‐oxygen vacancy) pairs and hence reduces the number density of Ti3+ trap states. Second, Co doping upshifts the band structure of TiO2, facilitating efficient charge extraction. As a result, for planar PSCs, the flame doping of Co increases the efficiency from 17.1% to 18.0% while reducing the hysteresis from 16.0% to 1.7%. Similarly, for mesoscopic PSCs, the flame doping of Co increases the efficiency from 18.5% to 20.0% while reducing the hysteresis from 7.0% to 0.1%. A rapid flame‐processed cobalt‐doped TiO2 for highly efficient perovskite solar cells with resolved hysteresis is described. The flame doping of Co2+ forms cobalt‐oxygen vacancy pairs in the TiO2 lattice that reduces the intrinsic defective Ti3+ and upshifts the band structure of TiO2, solving the current density‐voltage (J–V) hysteresis and enhancing the efficiency of both mesoscopic and planar perovskite solar cells. [ABSTRACT FROM AUTHOR]

To further increase the open‐circuit voltage (Voc) of perovskite solar cells (PSCs), many efforts have been devoted to doping the TiO2 electron transport/selective layers by using metal dopants with higher electronegativity than Ti. However, those dopants can introduce undesired charge traps that hinder charge transport through TiO2, so the improvement in the Voc is often accompanied by an undesired photocurrent density–voltage (J–V) hysteresis problem. Herein, it is demonstrated that the use of a rapid flame doping process (40 s) to introduce cobalt dopant into TiO2 not only solves the J–V hysteresis problem but also increases the Voc and power conversion efficiency of both mesoscopic and planar PSCs. The reasons for the simultaneous improvements are two fold. First, the flame‐doped Co‐TiO2 film forms Co‐Ov (cobalt dopant‐oxygen vacancy) pairs and hence reduces the number density of Ti3+ trap states. Second, Co doping upshifts the band structure of TiO2, facilitating efficient charge extraction. As a result, for planar PSCs, the flame doping of Co increases the efficiency from 17.1% to 18.0% while reducing the hysteresis from 16.0% to 1.7%. Similarly, for mesoscopic PSCs, the flame doping of Co increases the efficiency from 18.5% to 20.0% while reducing the hysteresis from 7.0% to 0.1%. A rapid flame‐processed cobalt‐doped TiO2 for highly efficient perovskite solar cells with resolved hysteresis is described. The flame doping of Co2+ forms cobalt‐oxygen vacancy pairs in the TiO2 lattice that reduces the intrinsic defective Ti3+ and upshifts the band structure of TiO2, solving the current density‐voltage (J–V) hysteresis and enhancing the efficiency of both mesoscopic and planar perovskite solar cells. [ABSTRACT FROM AUTHOR]

Nitride perovskites have only been experimentally realized in very few cases despite the widespread existence and commercial importance of perovskite materials. From oxide perovskites used in ultrasonics to halide perovskites that have revolutionized the photovoltaics industry, the discovery of new perovskite materials has historically impacted a wide number of fields. Here, we add two new perovskites, CeWN 3 and CeMoN 3 , to the list of experimentally realized perovskite nitrides using high-throughput computational screening and subsequent high-throughput thin film growth techniques. Candidate compositions are first down-selected using a tolerance factor and then thermochemical stability. A novel competing fluorite-family phase is identified for both material systems, which we hypothesize is a transient intermediate phase that crystallizes during the evolution from an amorphous material to a stable perovskite. Different processing routes to overcome the competing fluorite phase and obtain phase-pure nitride perovskites are demonstrated for the CeMoN 3- x and CeWN 3- x material systems, which provide a starting point for the development of future nitride perovskites. Additionally, we find that these new perovskite phases have interesting low-temperature magnetic behavior: CeMoN 3- x orders antiferromagnetically below T N ≈ 8 K with indications of strong magnetic frustration, while CeWN 3- x exhibits no long-range order down to T = 2 K but has strong antiferromagnetic correlations. This work demonstrates the importance and effectiveness of using high-throughput techniques, both computational and experimental: they are integral to optimize the process of realizing two entirely novel nitride perovskites., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

A surface disordered layer is a plausible approach to improve the photoelectrochemical performance of TiO 2 . However, the formation of a crystalline disordered layer in BiVO 4 and its effectiveness towards photoelectrochemical water splitting has remained a big challenge. Here, we report a rapid solution process (within 5 s) that is able to form a disordered layer of a few nanometers thick on the surface of BiVO 4 nanoparticles using a specific solution with a controllable reducing power. The disordered layer on BiVO 4 alleviates charge recombination at the electrode-electrolyte interface and reduces the onset potential greatly, which in turn results in a photocurrent density of approximately 2.3 mA cm -2 at 1.23 V versus the reversible hydrogen electrode (RHE). This value is 2.1 times higher than that of bare BiVO 4 . The enhanced photoactivity is attributed to the increased charge separation and transfer efficiencies, which resolve the intrinsic drawbacks of bare BiVO 4 such as the short hole diffusion length of around 100 nm and poor surface oxygen evolution reactivity., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)