Bilayered Two-Dimensional Hybrid Perovskite with the Cage-Templated Secondary Cation for High Efficiency Photodetection

Two-dimensional (2D) multilayered hybrid perovskites adopting the intrinsic quantum-well structures have shown great application potentials in the field of optoelectronics. Despite extensive studies, the candidate perovskites composed of the cage-templated...

Impact of carrier diffusion on internal quantum efficiency of InGaN quantum well structures

Internal quantum efficiency (IQE) is studied in a large set of polar and non-polar InGaN/GaN quantum well structures, 57 samples in total. In search for universal factors limiting IQE, the...

Modulation and optimization of terahertz absorption in micro-cavity quantum well structures by graphene grating

Metal-insulator-metal (MIM)-based plasmonic microcavity has attracted widespread interest due to its ability in manipulating and concentrating photons on the sub-wavelength scale. However, noble metals suffer from large intrinsic loss and lack active tunability. Here, a micro-cavity structure of quantum well sandwiched between periodic top contact of graphene grating and bottom contact graphene was proposed. Graphene plasmons provide a suitable alternative for metal plasmons and provide the advantage of being highly tunable by electrostatic gating. Effect of changes in both graphene physical and device structural parameters on optimized absorption performance was systematically analyzed through the calculation of reflectivity curves of incident light. Our results indicate that intersubband absorption of device can be improved by adjusting parameters of both graphene material and device structure. Furthermore, cavity resonant mode excited by surface plasmon polariton can be tuned to response frequency of quantum well under optimized parameters. Intersubband absorption is almost 1.5 times higher than that of a micro-cavity structure that uses metal grating.

Resonant tunneling driven metal-insulator transition in double quantum-well structures of strongly correlated oxide

The metal-insulator transition (MIT), a fascinating phenomenon occurring in some strongly correlated materials, is of central interest in modern condensed-matter physics. Controlling the MIT by external stimuli is a key technological goal for applications in future electronic devices. However, the standard control by means of the field effect, which works extremely well for semiconductor transistors, faces severe difficulties when applied to the MIT. Hence, a radically different approach is needed. Here, we report an MIT induced by resonant tunneling (RT) in double quantum well (QW) structures of strongly correlated oxides. In our structures, two layers of the strongly correlated conductive oxide SrVO3 (SVO) sandwich a barrier layer of the band insulator SrTiO3. The top QW is a marginal Mott-insulating SVO layer, while the bottom QW is a metallic SVO layer. Angle-resolved photoemission spectroscopy experiments reveal that the top QW layer becomes metallized when the thickness of the tunneling barrier layer is reduced. An analysis based on band structure calculations indicates that RT between the quantized states of the double QW induces the MIT. Our work opens avenues for realizing the Mott-transistor based on the wave-function engineering of strongly correlated electrons.

Advances and Challenges in Two-Dimensional Organic–Inorganic Hybrid Perovskites Toward High-Performance Light-Emitting Diodes

Two-dimensional (2D) perovskites are known as one of the most promising luminescent materials due to their structural diversity and outstanding optoelectronic properties. Compared with 3D perovskites, 2D perovskites have natural quantum well structures, large exciton binding energy (Eb) and outstanding thermal stability, which shows great potential in the next-generation displays and solid-state lighting. In this review, the fundamental structure, photophysical and electrical properties of 2D perovskite films were illustrated systematically. Based on the advantages of 2D perovskites, such as special energy funnel process, ultra-fast energy transfer, dense film and low efficiency roll-off, the remarkable achievements of 2D perovskite light-emitting diodes (PeLEDs) are summarized, and exciting challenges of 2D perovskite are also discussed. An outlook on further improving the efficiency of pure-blue PeLEDs, enhancing the operational stability of PeLEDs and reducing the toxicity to push this field forward was also provided. This review provides an overview of the recent developments of 2D perovskite materials and LED applications, and outlining challenges for achieving the high-performance devices."Image missing"