Metal halides have been demonstrated to be 1 promising candidates for X-ray detectors. However, its large 2 leakage current caused by the severe ion migration and 3 intrinsic defect substantially degrades device performance. 8 (0.80 eV) and conductivity mutation at the interface ensure 9 stable baseline and suppress leakage current; 2) CsPbI 3 10 ensures effective absorption of X-ray, while BA 2 CsPb 2 I 7 11 induces larger bulk resistance, which is expected to achieve 12 higher photocurrent and lower dark current. Finally, the 13 obtained X-ray detector exhibits negligible baseline drift, 14 faster response, and smaller leakage current compared to 15 the CsPbI 3 counterparts. Specifically, the device exhibits 16 a detection limit of 0.092 μGy air /s, and the CsPbI 3 -based 17 device was 2.63 μGy air /s.

The discovery of carbon‐based quantum dots (CQDs) has allowed opportunities for fluorescence bioimaging, tumor diagnosis and treatment, and photo‐/electro‐catalysis. Nevertheless, in the existing reviews related to the “bottom‐up” approaches, attention is mainly paid to the applications of CQDs but not the formation mechanism of CQDs, which mainly derived from the high complexities during the synthesis of CQDs. Among the various synthetic methods, using small molecules as “building blocks”, the development of a “bottom‐up” approach has promoted the structural design, modulation of the photoluminescence properties, and control of the interfacial properties of CQDs. On the other hand, many works have demonstrated the “building blocks”‐dependent properties of CQDs. In this review, from one of the most important variables, the relationships among intrinsic properties of “building blocks” and photoluminescence properties of CQDs are summarized. The topology, chirality, and free radical process are selected as descriptors for the intrinsic properties of “building blocks”. This review focuses on the induction and summary of recent research results from the “bottom‐up” process. Moreover, several empirical rules pertaining thereto are also proposed.

Nitrogen‐doped three‐dimensional graphene (N‐doped 3D‐graphene) is a graphene derivative with excellent adsorption capacity, large specific surface area, high porosity, and optoelectronic properties. Herein, N‐doped 3D‐graphene/Si heterojunctions were grown in situ directly on silicon (Si) substrates via plasma‐assisted chemical vapor deposition (PACVD), which is promising for surface‐enhanced Raman scattering (SERS) substrates candidates. Combined analyses of theoretical simulation, incorporating N atoms in 3D‐graphene are beneficial to increase the electronic state density of the system and enhance the charge transfer between the substrate and the target molecules. The enhancement of the optical and electric fields benefits from the stronger light‐matter interaction improved by the natural nano‐resonator structure of N‐doped 3D‐graphene. The as‐prepared SERS substrates based on N‐doped 3D‐graphene/Si heterojunctions achieve ultra‐low detection for various molecules: 10−8 M for methylene blue (MB) and 10−9 M for crystal violet (CRV) with rhodamine (R6G) of 10−10 M. In practical detected, 10−8 M thiram was precisely detected in apple peel extract. The results indicate that N‐doped 3D‐graphene/Si heterojunctions based‐SERS substrates have promising applications in low‐concentration molecular detection and food safety.

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Interface engineering is a simple and effective strategy for improving the photovoltaic performance and stability of perovskite solar cells (PSCs). Herein, an interface co-modification strategy is proposed, using [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and 2-fluoro-1,4-phenylenediammonium iodide (2FPPD) to modify the electron transport layer (ETL)/perovskite (PVK) and the PVK/hole transport layer (HTL) interfaces, respectively. A series of characterizations demonstrate that the PCBM&2FPPD interface co-modification strategy effectively enhances the extraction and transport efficiency of carriers at the interface, passivates surface defects, inhibits the nonradiative recombination of carriers, and simultaneously inhibits ion migration. Moreover, this strategy improves the crystallinity and surface hydrophobicity of PVK and optimizes the energy level alignment of PSCs. As a result, all photovoltaic parameters are improved after optimization, where the power conversion efficiency (PCE) of PSCs has increased from 17.01% to 18.36%. Meanwhile, the optimized PSCs show excellent environmental stability, which can be stably stored in air (RH = 10−20%) for about 800 h.