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Photogenerated carrier behavior at a CO2/Cs2AgBiBr6 quantum dot (QD) interface is investigated. In situ photovoltage spectra reveal electron transfer from the Cs2AgBiBr6 QDs to CO2. Moreover, this carrier transfer prefers Bi3+ sites (over Ca+ and Ag+ sites) due to them exhibiting the lowest adsorption energy (Eads = −0.125 eV) and CO2–Bi3+ interactions being more stable. [ABSTRACT FROM AUTHOR]

Interface modification is an important means to enhance the photovoltaic performance of quantum dot sensitized solar cells (QDSCs). The TiO2/CdS/CdSe solar cells are sensitized with CdS QDs and CdSe QDs, which inevitably introduces a new interface to form a recombination center. Therefore, it is necessary to coat a passivation layer in order to effectively inhibit charge recombination at the CdS/CdSe interface. In this work, CuInS2 (CIS) has been introduced into the CdS/CdSe QD system as an inner passivation layer and the CdS/CIS/CdSe photoanode structure has been fabricated in an environmentally friendly manner. The extracted charge amount (Q) is used to express the charge separation efficiency, indicating that we have obtained outstanding charge extraction efficiency in CIS based CdS/CdSe QDSCs. As a result, the photocurrent density of the TiO2/CdS/CIS/CdSe photoanode significantly has increased from 19.01 mA cm−2 to 22.74 mA cm−2 (TiO2/CdS/CdSe photoanode), which demonstrates a higher photoconversion efficiency of 4.52% in comparison with that of TiO2/CdS/CdSe photoanode. [ABSTRACT FROM AUTHOR]

CsPbBr3 perovskite exhibits potential application in photocatalytic CO2 reduction into valuable chemical fuels; however, enhancing carrier separation capability of the CsPbBr3 and fully understanding the CO2 reduction reaction process are still imperative. Herein, a new series of xSnS2/CsPbBr3 nanocrystals (NCs)‐y heterostructures are developed, which exhibit better catalytic activity in comparison with pure CsPbBr3 NCs. Interface and surface carrier dynamic investigation reveals that this heterojunction structure can effectively improve carrier separation efficiency. Based on the interfacial electric field direction of CsPbBr3 to SnS2, it is suggested that SnS2/CsPbBr3 NC heterostructure satisfies Z‐scheme transfer dynamics. Meanwhile, by the aid of in situ surface photovoltage, it is experimentally confirmed there is dynamic carrier interaction between CO2 molecules and the SnS2/CsPbBr3 NCs photocatalyst under irradiation, and a photocatalytic CO2 reduction mechanism is thus proposed. This work expands the awareness of the interaction between CO2 and the photocatalyst, which can be strongly influenced by carrier separation efficiency at the photocatalyst heterojunction. [ABSTRACT FROM AUTHOR]

Ferroelectric hafnium oxide (HfO2) thin film has been widely studied as a promising material candidate for microelectronic devices. In this paper, HfO2/Hf/HfO2 stacked films were deposited by reactive magnetron sputtering to investigate the effects of metal Hf on the phase transition and electric properties. An interesting phenomenon is that HfO2 film inserted with a thin layer of metal Hf exhibits ferroelectricity after high-field cycling (wake-up). The generation of ferroelectricity is due to a region in HfO2 film with a gradient distribution of oxygen vacancies resulting in the formation of orthorhombic HfO2, which is caused by the oxidation of metal Hf in HfO2 film. Inserted with 0.2-nm-thick metal Hf layer, the stacked film shows the coercive field of 3.4 MV/cm and remanent polarization of 4.2 μC/cm2, respectively. An increase in the Hf layer thickness from 0.2 to 1.5 nm causes the leakage current density of the stacked film increasing from 8.2 × 10–6 to 6.2 × 10–4 A/cm2. The results provide a strong evidence for the important role of inhomogeneous oxygen vacancies played in introduction of the ferroelectricity of HfO2 film. [ABSTRACT FROM AUTHOR]