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A deep understanding of the dynamics of photogenerated charge carriers is extremely important for promoting their germination in semiconductors to enhance the efficiency of solar energy conversion. In contrast to that of organic molecular heterojunctions (which are widely employed in organic solar cells), the charge transfer dynamics of purely inorganic molecular heterojunctions remains unexplored. Herein, we reveal the dynamics of charge transfer between inorganic semiconductor molecular heteroclusters by selecting a group of open-framework metal chalcogenides as unique structure models constructed from supertetrahedral T3-InS ([In10S20]) and T4-MInS ([M4In16S35], M = Mn or Fe) clusters. The staggered band gap alignment in T3-T4-MInS molecular heterojunctions enables the photogenerated charge carriers to be directionally transferred from T3-InS clusters to adjacent T4-MInS clusters upon irradiation or application of an external electric field. The simultaneous independence of and interactions between such two heteroclusters are investigated by theoretical calculations, steady- and transient-state absorption/photoluminescence spectroscopy, and surface photovoltage analysis. Moreover, the dynamics of cluster-to-cluster-to-dopant photogenerated charge transfer is deliberately elucidated. Thus, this work demonstrates the direct observation of charge transfer between molecular heterojunctions based on purely inorganic semiconductor clusters and is expected to promote the development of cluster-based semiconductors for solar cells.

Three triphenylamine (TPA) substituted cyclometalated Ir(iii) complexes IrA1, IrA2, and IrA3 based on Ir(ppy)3 were synthesized and applied as phosphorescent probes for the monitoring of molecular oxygen. The phosphorescence intensity of all the Ir(iii) complexes in tetrahydrofuran (THF) was gradually quenched with an increase of oxygen concentration. The increase of TPA substituents on the meta-position of 2-phenylpyridine (IrA1-IrA3) gradually improved the oxygen sensitivity of cyclometalated Ir(iii) complexes. IrA3 showed the highest oxygen sensitivity in THF with a K app SV of 204.8 bar-1 and a limit of detection (LOD) of 0.27 mbar. The relationship between molecular structure and the collision radiuses (σ) of all the Ir(iii) complexes has been investigated on the basis of the Demas model and the fundamental expression of luminescence quenching systems by oxygen. The ratio of collision radiuses are σ IrA1/σ Ir(ppy)3 = 1.27 ± 0.05, σ IrA2/σ Ir(ppy)3 = 1.72 ± 0.10, and σ IrA3/σ Ir(ppy)3 = 2.13 ± 0.07, respectively. The introduction and increase of TPA substituents can obviously increase the collision radiuses of cyclometalated Ir(iii) complexes which leading to potential oxygen sensitivity. And the incremental effect of collision radiuses caused by the introduction of TPA substituents resulted in outstanding oxygen sensitivity of IrA3. The results demonstrate for the first time evidence between molecular structure and oxygen sensitivity of the emitters for optical sensing.

CO2 cycloaddition with epoxides is a key catalytic procedure for CO2 utilization. Several metal-based catalysts with cocatalysts are developed for photo-driven CO2 cycloaddition, while facing difficulties in product purification and continuous reaction. Here, poly(ionic liquid)s are proposed as metal-free catalysts for photo-driven CO2 cycloaddition without cocatalysts. A series of poly(ionic liquid)s with donor-acceptor segments are fabricated and their photo-driven catalytic performance (conversion rate of 83.5% for glycidyl phenyl ether) outstrips (≈4.9 times) their thermal-driven catalytic performance (17.2%) at the same temperature. Mechanism studies confirm that photo-induced charge separation is promoted by the donor-acceptor segments and can accelerate the CO2 cycloaddition reaction. This work paves the way for the further use of poly(ionic liquid)s as catalysts in photo-driven CO2 cycloaddition. [ABSTRACT FROM AUTHOR]

Triplet exciton‐based long‐lived phosphorescence is severely limited by the thermal quenching at high temperature. Herein, we propose a novel strategy based on the energy transfer from triplet self‐trapped excitons to Mn2+ dopants in solution‐processed perovskite CsCdCl3. It is found the Mn2+ doped hexagonal phase CsCdCl3 could simultaneously exhibit high emission efficiency (81.5 %) and long afterglow duration time (150 s). Besides, the afterglow emission exhibits anti‐thermal quenching from 300 to 400 K. In‐depth charge‐carrier dynamics studies and density functional theory (DFT) calculation provide unambiguous evidence that carrier detrapping from trap states (mainly induced by Cl vacancy) to localized emission centers ([MnCl6]4−) is responsible for the afterglow emission with anti‐thermal quenching. Enlightened by the present results, we demonstrate the application of the developed materials for optical storage and logic operation applications. [ABSTRACT FROM AUTHOR]

Recently, lanthanide‐doped halide perovskites have attracted increasing attention due to their unique optical properties, such as upconversion (UC) and near‐infrared (NIR) emission. However, these emitters suffer from low efficiency, limiting further practical applications. Herein, a Bi3+‐alloyed double perovskite, Cs2NaEr0.5Bi0.5Cl6, with strong NIR‐triggered UC and NIR‐II (1000–1700 nm) emission is reported. Cs2NaEr0.5Bi0.5Cl6 exhibits efficient green UC emission with a high quantum yield up to 2.1% and NIR‐II emission peaking at 1541 nm with a quantum yield of 37.9% under 980 nm excitation. The strong UC emission is related with the efficient energy transfer between Er3+ and self‐trapped exciton states induced by corporation of Bi3+ ions. In addition, Bi3+ ions can act as diluters, suppressing the energy loss caused by undesirable successive energy transfer among Er3+ ions, enhancing the UC and NIR‐II emission. Furthermore, a water‐resistant Cs2NaEr0.5Bi0.5Cl6/polydimethylsiloxane film is prepared. Excitingly, Cs2NaEr0.5Bi0.5Cl6 not only shows the potential as a UC thermometry with high sensitivity but also exhibits a high signal to noise ratio in NIR imaging. [ABSTRACT FROM AUTHOR]