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Abstract: BiOCl nanosheets/TiO2 nanotube arrays heterojunction UV photodetector (PD) with high performance is fabricated by a facile anodization process and an impregnation method. The heterojunction at the interface and the internal electric fields in the BiOCl nanosheets faciliate the separation of photogenerated charge carriers and regulate the transportation of the electrons. Compared with the large dark current (≈10−5 A), low on/off ratio (8.5), and slow decay time (>60 s) of the TiO2 PD, the optimized heterojunction PD (6‐BiOCl–TiO2) yields dramatically decreased dark current (≈1 nA), ultrahigh on/off ratio (up to 2.2 × 105), and fast decay speed (0.81 s) under 350 nm light illumination at −5 V. Moreover, it exhibits an increased responsivity of 41.94 A W−1, a remarkable detectivity (D*) of 1.41 × 1014 Jones, and a high linear dynamic range of 103.59 dB. The loading amount and growth orientations of the BiOCl nanosheets alter the roles of the self‐induced internal electric field in regulating the behaviors of the charge carriers, thus affecting the photoelectric properties of the heterojunction PDs. These results demonstrate that rational construction of novel heterojunctions hold great potentials for fabricating photodetectors with high performance. [ABSTRACT FROM AUTHOR]

Abstract: Single crystal microwires of a well‐studied organic semiconductor used in organic solar cells, namely p‐DTS(FBTTh2)2, are prepared via a self‐assembly method in solution. The high level of intermolecular organization in the single crystals facilitates migration of charges, relative to solution‐processed films, and provides insight into the intrinsic charge transport properties of p‐DTS(FBTTh2)2. Field‐effect transistors based on the microwires can achieve hole mobilities on the order of ≈1.8 cm2 V−1 s−1. Furthermore, these microwires show photoresponsive electrical characteristics and can act as photoswitches, with switch ratios over 1000. These experimental results are interpreted using theoretical simulations using an atomistic density functional theory approach. Based on the lattice organization, intermolecular couplings and reorganization energies are calculated, and hole mobilities for comparison with experimental measurements are further estimated. These results demonstrate a unique example of the optoelectronic applications of p‐DTS(FBTTh2)2 microwires. [ABSTRACT FROM AUTHOR]

Broadband responsivity enhancement of single Se microtube (Se-MT) photodetectors in the UV-visible region is presented in this research. The pristine Se-MT photodetector demonstrates broadband photoresponse from 300 to 700 nm with peak responsivity of ≈19 mA W−1 at 610 nm and fast speed (rise time 0.32 ms and fall time 23.02 ms). To further enhance the responsivity of the single Se-MT photodetector, Au and Pt nanoparticles (NPs) are sputtered on these devices. In contrast to only enhancement of responsivity in UV region by Pt NPs, broadband responsivity enhancement (≈600% to ≈800%) of the Se-MT photodetector is realized from 300 to 700 nm by tuning the size and density of Au NPs. The broadband responsivity enhancement phenomena are interpreted by both the surface modification and surface plasmon coupling. The experimental results of this work provide an additional opportunity for fabricating high-performance UV-visible broadband photodetectors. [ABSTRACT FROM AUTHOR]

Unlocking the afterglow properties of the fluorescence molecules at room temperature is an urgent challenge. Herein, inks prepared with dimethyl terephthalate (DTT) and carbazole (Cz) analogs with heteroatom (C, S, and O) substituents on the N as host and guest molecules can be directly sprayed onto different substrates to unlock the excitation‐wavelength dependent (Ex‐De) afterglow characteristics of the guest compound. Additionally, with the increase in the number of lone pair electrons, spin‐orbit coupling (SOC) increases, resulting in a longer afterglow duration lasting up to 4.5 s with Φp>27%. Theory calculations and experiments indicate that the afterglow originated from the interactions between the host and guest molecules restricting the non‐radiative transition of the triplet excitons. Different Ex (with watershed at 310 nm) lead to the variation in the conformation of the S0DTT and S1DTT, which in turn affects the strength of host‐guest interactions and contributes to the Ex‐De characteristics. Benefiting from facile preparation, substrate‐independent applicability, and Ex‐De characteristics, the afterglow samples are demonstrated for applications in multilevel information security fields. This work proposes a general strategy for unlocking the afterglow emission of traditional molecules, which is valuable for the discovery of high‐performance afterglow materials in the future. [ABSTRACT FROM AUTHOR]