Single crystal is the most advantageous of the crystalline states of halide perovskites. It displays better optical and electrical capabilities than polycrystalline films and microcrystals due to their inherent structural advantages, such as free grain boundaries, long-range ordered structure, and high orientation. Single-crystal perovskite materials can theoretically enable optoelectronic devices with higher performance and stronger stability. In this review, the intrinsic physical properties of perovskite single crystals are analyzed. The most recent advances in single-crystal optoelectronic devices are reviewed, and the design principles of the devices under different application conditions are revealed. It provides potential solutions for remaining challenges, and it is expected to accelerate the development of perovskite based optoelectronic devices.

Even in their bulk forms, complex alloys like high-entropy alloys (HEAs) exhibit favorable activity and stability as electrocatalysts for the oxygen evolution reaction (OER). However, the underlying reasons are not yet fully understood. In a family of Mo-doped CrFeCoNi-based HEAs, we have identified three crucial factors that govern their performance: (i) homogeneous solid solution phase of HEAs helps to maintain high-valence states of metals; (ii) surface reconstruction results in a hybrid material comprising amorphous domains and percolated crystalline structures; (iii) diversity of active intermediate species (M–O, M–OOH, and, notably, the abundance of superoxide μ–OO), which display stronger adsorption capacity on the reconstructed surface. These results are revealing due to their resemblance to findings in other families of electrocatalysts for OER, as well as their unique features specific to HEAs. In line with these factors, a CrFeCoNiMo0.2 bulk integrated electrode displays a low overpotential of 215 mV, rapid kinetics, and long-term stability of over 90 d. Bulk HEAs hold great potential for industrial applications.

Photovoltaic (PV)-integrated flow cells for electrochemical energy conversion and storage underwent a huge development. The advantages of this type of integrated flow cell system include the simultaneous storage of solar energy into chemicals that can be readily utilized for generating electricity. However, most studies overlook the practical challenges arising from the inherent heat exposure and consequent overheating of the reactor under the sun. This work aims to predict the temperature profiles across PV-integrated electrochemical flow cells under light exposure conditions by introducing a computational fluid dynamics–based method. Furthermore, we discuss the effects of the flow channel block architecture on the temperature profile to provide insights and guidelines for the effective remedy of overheating.