The schematic diagram of different Sn-5s and I-5p antibonding strengths of FASnI3 and MASnI3 due to various bond lengths of Sn–I.

Controlled morphology modulation of graphene carbon nitride (g-C 3 N 4 ) is successfully realized from bulk to 3D loose foam architecture via the blowing effect of a bubble, which can be controlled by heating rate. The loose foam network is comprised by spatially scaffolded few-atom-layer interconnected flakes with the large specific surface area, as supporters to prevent agglomeration and provide a pathway for electron/phonon transports. The photocatalytic performance of 3D foam strutted g-C 3 N 4 toward RhB decomposition and hydrogen evolution is significantly enhanced with the morphology optimization while its excellent optoelectronic properties are maintained simultaneously. Herein, the ultrathin, mono-, and high-quality foam g-C 3 N 4 interconnected flakes with controlled layer are facilely obtained through ultrasonic, thus overcoming the drawbacks of a traditional top-down approach, opening a wide horizon for diverse practical usages. Additionally, the layer control mechanism of 3D hierarchical structure has been explored by means of bubble growth kinetics analysis and the density functional theory calculations.

Point defects play an important role in the photoelectrical properties of semiconductor materials, and they can be luminescence centers. However, the relationships among the observed luminescence wavelengths, intensities, and the microscopic processes are in most cases unknown, or depend heavily on parameter fitting. In this work, the light‐emitting quantum efficiencies for point defects using ab initio density functional theory are calculated. The study of radiation recombination for electrons and nonradiation recombination for holes is reported here. The results show that the defect CN transition between “−” and “0” charged levels and the defect CN+ON transition between “0” and “+” charged levels both may be responsible for the yellow luminescence (YL) which is observed in experiment. Moreover, the calculation shows significant thermal quenching of the YL starting at 480 K due to re‐excitation of hole into the valence band from the point defects, which is in relatively good agreement with the experimentally observed value. This work shows that it is possible to use ab initio calculations to understand the microscopic mechanisms and the competitions among different channels for the light emissions caused by defects.