Carrier transfer in quasi-2D perovskite/MoS monolayer heterostructure.

Two-dimensional layered semiconductors have attracted intense interest in recent years. The van der Waals coupling between the layers tolerates stacking various materials and establishing heterostructures with new characteristics for a wide range of optoelectronic applications. The interlayer exciton dynamics at the interface within the heterostructure are vitally important for the performance of the photodetector and photovoltaic device.

Ultrafast energy transfer dynamics in CsPbBr nanoplatelets-BODIPY heterostructure.

Understanding and directing the energy transfer in nanocrystals-chromophore heterostructure is critical to improve the efficiency of their photocatalytic and optoelectronic applications. In this work, we studied the energy transfer process between inorganic-organic molecular complexes composed of cesium halide perovskite nanoplatelets (CsPbBr NPLs) and boron dipyrromethene (BODIPY) by photoluminescence spectroscopy (PL), time-correlated single photon-counting (TCSPC) and femtosecond transient absorption spectroscopy. The quenching of PL in CsPbBr NPLs occurred simultaneously with the PL enhancement of BODIPY implied the singlet energy transfer process.

Design of BPEA-based derivatives with high singlet fission performance: a theoretical perspective.

The development of singlet fission (SF) is greatly hindered by the severe shortage of the types and numbers of SF materials. Here, essential energy conditions and SF-related competitive processes of a series of BPEA derivatives, which are a kind of new promising SF material, are investigated theoretically. Encouraging advantages and interesting laws of key energy conditions of those derivatives were found and potential BPEA derivatives were predicted.

Observation of carrier transfer in a vertical 0D-CsPbBr/2D-MoS mixed-dimensional van der Waals heterojunction.

Two-dimensional transition metal dichalcogenides with outstanding properties open up a new way to develop optoelectronic devices such as phototransistors and light-emitting diodes. Heterostructure with light-harvesting materials can produce many photogenerated carriers via charge and/or energy transfer. In this paper, the ultrafast dynamics of charge transfer in zero-dimensional CsPbBr quantum dot/two-dimensional MoS van der Waals heterostructures are investigated through femtosecond time-resolved transient absorption spectroscopy.

Multiexciton dynamics in CsPbBrnanocrystals: the dependence on pump fluence and temperature.

Multiexcitons generation is a process of generating electron-hole pairs in nanostructured semiconductors by absorbing a single high-energy photon. The multiexciton process is essential for the performance of optoelectronic devices based on perovskite nanomaterials. In this paper, ultrafast time-resolved transient absorption spectroscopy is used to study the ultrafast dynamics of CsPbBrnanocrystals.

Identification of a bridge-specific intramolecular exciton dissociation pathway in donor-π-acceptor alternating conjugated polymers.

Intramolecular exciton dissociation is critical for high efficient mobile charge carrier generations in organic solar cells. Yet despite much attention, the effects of π bridges on exciton dissociation dynamics in donor-π-acceptor (D-π-A) alternating conjugated polymers remain still unclear. Here, using a combination of femtosecond time-resolved transient absorption (TA) spectroscopy and steady-state spectroscopy, we track ultrafast intramolecular exciton relaxation dynamics in three D-π-A alternating conjugated polymers which were synthesized by Qin's group and named HSD-A, HSD-B, HSD-C.

Excitation Wavelength and Intensity-Dependent Multiexciton Dynamics in CsPbBr Nanocrystals.

CsPbBr3 has attracted great attention due to unique optical properties. The understanding of the multiexciton process is crucial for improving the performance of the photoelectric devices based on CsPbBr3 nanocrystals. In this paper, the ultrafast dynamics of CsPbBr3 nanocrystals is investigated by using femtosecond transient absorption spectroscopy.

Hot excitons cooling and multiexcitons Auger recombination in PbS quantum dots.

In the past few years, lead chalcogenide quantum dots (QDs) have attracted attention as a new system with a strong quantum confinement effect. In this paper, the hot-excitons cooling and Auger recombination of multiexcitons in PbS QDs are investigated by the femtosecond time-resolved transient absorption spectroscopy. The results show that the excitons dynamics in PbS QDs are closely related to the pump-photon energy and pump-pulse energy.

Tunable Schottky barrier in InTe/graphene van der Waals heterostructure.

The structures and electronic properties of InTe/graphene van der Waals heterostructures are systematically investigated using the first-principles calculations. The electronic properties of InTe monolayer and graphene are well preserved respectively and the bandgap energy of graphene is opened to 36.5 meV in the InTe/graphene heterostructure.

Interfacial States and Fano-Feshbach Resonance in Graphene-Silicon Vertical Junction.

Interfacial quantum states are drawing tremendous attention recently because of their importance in design of low-dimensional quantum heterostructures with desired charge, spin, or topological properties. Although most studies of the interfacial exchange interactions were mainly performed across the interface vertically, the lateral transport nowadays is still a major experimental method to probe these interactions indirectly. In this Letter, we fabricated a graphene and hydrogen passivated silicon interface to study the interfacial exchange processes.

Schottky barrier modulation of a GaTe/graphene heterostructure by interlayer distance and perpendicular electric field.

Two-dimensional materials have recently been the focus of extensive research. Graphene-based vertical van der Waals heterostructures are expected to design and fabricate novel electronic and optoelectronic devices. Monolayer gallium telluride is a graphene-like nanosheet synthesized in experiment.

Tuning Electronic Properties of Blue Phosphorene/Graphene-Like GaN van der Waals Heterostructures by Vertical External Electric Field.

The structural and electronic properties of a monolayer and bilayer blue phosphorene/graphene-like GaN van der Waals heterostructures are studied using first-principle calculations. The results show that the monolayer-blue phosphorene/graphene-like GaN heterostructure is an indirect bandgap semiconductor with intrinsic type II band alignment. More importantly, the external electric field tunes the bandgap of monolayer-blue phosphorene/graphene-like GaN and bilayer-blue phosphorene/graphene-like GaN, and the relationship between bandgap and external electric field indicates a Stark effect.

Tunable Electric Properties of Bilayer α-GeTe with Different Interlayer Distances and External Electric Fields.

Based on first-principle calculations, the stability, electronic structure, optical absorption, and modulated electronic properties by different interlayer distances or by external electric fields of bilayer α-GeTe are systemically investigated. Results show that van der Waals (vdW) bilayer α-GeTe has an indirect band structure with the gap value of 0.610 eV, and α-GeTe has attractively efficient light harvesting.

Ferromagnetic Properties of N-Doped and Undoped TiO₂ Rutile Single-Crystal Wafers with Addition of Tungsten Trioxide.

In this work, undoped, N-doped, WO₃-loaded undoped, and WO₃-loaded with N-doped TiO₂ rutile single-crystal wafers were fabricated by direct current (DC) magnetron sputtering. N-doping into TiO₂ and WO₃ loading onto TiO₂ surface were used to increase and decrease oxygen vacancies. Various measurements were conducted to analyze the structural and magnetic properties of the samples.