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The performance of perovskite solar cells (PSCs), especially for the parameters of open-circuit voltage (Voc) and fill factor, is seriously restricted by the unavoidable interfacial charge recombination. In this study, an ultrawide band gap semiconductor material of Ga2O3is introduced between fluorine-doped tin oxide and SnO2to regulate the interfacial charge dynamics by forming the Ga2O3/SnO2electron-transporting bilayer. Ga2O3has an appropriate conduction band minimum which benefits the electron transport, and at the same time, it has a very deep valence band maximum which could be regarded as an effective blocking layer. Such an innovative structure triggers the advantages of a lower work function and a smoother surface of the electron-transporting bilayer which leads to a high-quality perovskite film. Furthermore, superior hole-blocking properties of the introduced Ga2O3layer could effectively reduce the interfacial recombination. All the properties could help to improve the extracting and transporting ability of charge carriers synergistically. Finally, the efficiency and stability of PSCs are greatly enhanced. All results suggest that the performance of PSCs could be improved effectively by introducing the ultrawide band gap oxide semiconductor of Ga2O3.

All-inorganic, Cl-based perovskites are promising for visible-blind UV photodetectors (PDs), particularly the self-powered ones. However, the devices are rarely reported until now since the low solubility of raw materials hinders significantly the thickness and electronic quality of solution-processed Cl-based perovskite films. Herein, we demonstrate a simple intermediate phase halide exchange method to prepare desired dual-phase CsPbCl3–Cs4PbCl6films. It is achieved by spin-coating of a certain dose of CH3NH3Cl/CsCl solution onto a CsI–PbBr2–dimethyl sulfoxide (DMSO) intermediate phase film, followed by thermal annealing. The inclusion of CsCl species in the solution is crucial to a stable dual-phase CsPbCl3–Cs4PbCl6film, while a high annealing temperature contributes to improving its quality. Therefore, the dual-phase CsPbCl3–Cs4PbCl6film with an absorption onset of ∼420 nm, microsized grains, a few defects, and a proper work function is obtained by optimizing the annealing temperature. The final self-powered, visible-blind UV PD exhibits the superior performance, including a favored response range of 310–420 nm, a high responsivity (R) peak value of 61.8 mA W–1, an exceptional specific detectivity (D*) maximum of 1.35 × 1012Jones, and a particularly fast response speed of 2.1/5.3 μs, together with amazing operational stability. This work represents the first demonstration of solution-processed, self-powered, visible-blind UV PDs with all-inorganic, Cl-based perovskite films.

Inorganic halide perovskite CsPbBr3is emerging as one of the promising alternatives to the hybrid counterparts for optoelectronic applications owing to its upgraded stability. Yet, the inherently low solubility of a CsBr precursor material restricts the quality and especially the thickness of a solution-processed CsPbBr3film, thus hindering the further optimization of device performance. Herein, we report a facile intermediate phase halide exchange reaction that can break the thickness limit of a solution-processed CsPbBr3film, since it avoids the use of low-solubility CsBr. Furthermore, the CH3NH3I byproduct after halide exchange could trigger a beneficial Ostwald ripening process to promote grain coarsening in the film. Hence, the uniformly flat, pure-phase, and compact CsPbBr3film composed of [100] preferential, microsized grains can be achieved. As a demonstration of its excellent optoelectronic features, the carbon-based, all-inorganic photodetector with such a favorable film yields a maximum photoresponsivity of 0.35 A W–1and a specific detectivity of 1.94 × 1013Jones coupled with a response time of 0.58 μs.

Inorganic halide perovskite CsPbIBr2possesses the most balanced band gap and stability characters among all of the concerned analogs for carbon-based, all-inorganic solar cells that are free of any hole-transporting layers and noble-metal electrodes. Yet, the current CsPbIBr2solar cells seem to deliver the lowest record efficiency. This is originally plagued by a serious energy loss (Eloss) in the cells, which thus limits their open-circuit voltages (Voc) severely. Herein, we demonstrate a light-processing technology that can overcome this obstacle successfully, by enabling the full-coverage, pure-phase CsPbIBr2films featured with large grains, high crystallinity, and preferential [100] grains orientation, along with favorable electronic structure. It is achieved by the exposure of CsPbIBr2precursor film formed in a conventional one-step spin-coating route to a simulated AM 1.5 G illumination before thermal annealing. The resulting carbon-based, all-inorganic planar cells give an optimized power conversion efficiency (PCE) of 8.60% with the Vocof 1.283 V. Notably, such an impressive Vocstands the highest value among all of the previously reported CsPbIBr2solar cells; hence, its PCE exceeds nearly all of them. Therefore, our work suggests a new route to further improve the efficiency of low-cost, stable, and simple-fabrication CsPbIBr2solar cells.