Reduced dimensional lead halide perovskites (RDPs) have attracted great research interest in diverse optical and optoelectronic fields. However, their poor stability is one of the most challenging obstacles prohibiting them from practical applications. Here, we reveal that ultrastable laurionite-type Pb(OH)Br can spontaneously encapsulate the RDPs in their formation solution without introducing any additional chemicals, forming RDP@Pb(OH)Br core− shell microparticles. Interestingly, the number of the perovskite layers within the RDPs can be conveniently and precisely controlled by varying the amount of CsBr introduced into the reaction solution. A single RDP@Pb(OH)Br core−shell microparticle composed of RDP nanocrystals with different numbers of perovskite layers can be also prepared, showing different colors under different light excitations. More interestingly, barcoded RDP@Pb(OH)Br microparticles with different parts emitting different lights can also be prepared. The morphology of the emitting microstructures can be conveniently manipulated. The RDP@ Pb(OH)Br microparticles demonstrate outstanding environmental, chemical, thermal, and optical stability, as well as strong resistance to anion exchange processes. This study not only deepens our understanding of the reaction processes in the extensively used saturation recrystallization method but also points out that it is highly possible to dramatically improve the performance of the optoelectronic devices through manipulating the spontaneous formation process of Pb(OH)Br.

CsPbBr3 film possesses high stability and easy manufacturing characteristics, rendering it attractive for applications in perovskite solar cells (PSCs). However, optical loss and energy level matching of different material layers are still the major factors, limiting the performance of PSCs. Herein, the finite element method (FEM) and density functional theory (DFT) calculations composed of simulation interaction technology are used to study the effects of different electron transport layer and hole transport layer materials on the optical performance of different PSC configurations. The effect of the charge transport layer (CTL) material and CsPbBr3 on the energy level matching and charge transport of the device is explained. The FEM simulation results show that inorganic CTL materials produce less parasitic absorption than the organic materials. The DFT calculation results give the microscopic design rules of the CTL material. In addition, PSCs with a light‐trapping structure are designed, which effectively suppressed surface reflection. Finally, through the screening of CTL materials and the design of advanced light‐trapping structures, the photocurrent of PSCs is increased by 69.8% (from 5.30 to 9.00 mA cm−2). This work provides a novel model for the screening of CTL materials for inorganic PSCs.

The application of accumulated electron sites on the catalyst surface for photocatalytic hydrogen production represents a prospective strategy for efficient utilization of solar energy. Herein, the accumulated electron sites (BN2) loaded on graphitic carbon nitride (G-CN) were prepared without effort by a two-step calcination method in which melamine was calcined and then heat-treated with NaBH4. When compared with that of the bulk G-CN, the rate toward water splitting to produce H2 of the represented catalyst (CN-B0.05) greatly increased by 2.3 times under illumination (λ ≥ 420 nm). The improved activity could be attributed to the decrease in interlayer distance and the potential barrier of interlayers which was beneficial to readily transfer electrons in the Z direction, improve the adsorption and activation of water, and decline the Gibbs free energies for H* adsorption. The increase in π–π conjugation facilitated enhancement of the separation efficiency of photogenerated electron–hole pairs and light-capturing capabilities in the visible region with the introduction of BN2 sites. An approach for efficient H2 production is demonstrated in this work.

It is anticipated that perovskite solar cells (PSCs) will overtake other products in the market for next‐generation photovoltaics. The optical loss, however, continues to be a flaw that restricts the photocurrent (Jph) of PSCs. Mesoporous antireflection coatings (ARCs), both monolayer and multilayer, are designed using a combination of the finite element method and equivalent medium theory, and ARCs models are merged with PSCs. In the current work, mesoporous ARCs are made, the optical performance of the device is evaluated using optical modeling, and then the ARCs are integrated into solar cells. The simulation results show that the Jph of planar inverted PSCs can increase to 24.00 mA cm−2 when the front surface of PSCs adopts mesoporous ARC (via parameter optimization and sensible arrangement and combination). An increase of 0.98 mA cm−2 in Jph of PSCs is observed in comparison with flat ARC (23.02 mA cm−2). The strong light transmission and low reflection properties of the mesoporous ARCs are confirmed by the optimized solution. It is important to note that the first fusion of mesoporous and multilayer ARC offers a fresh approach to the development of perovskite and perovskite/silicon tandem solar cells with extremely high efficiency.