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Potential well
About: Potential well is a research topic. Over the lifetime, 1430 publications have been published within this topic receiving 30812 citations.
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TL;DR: In this paper, the 1D interface exciton has giant binding energy in the same order as 2D excitons in pristine monolayer TMDs, although the effective radius (electron-hole separation) of interfaceexciton is much larger than that of 2Dexcitons.
Abstract: We study the interface exciton at lateral type II heterojunctions of monolayer transition metal dichalcogenides (TMDs), where the electron and hole prefer to stay at complementary sides of the junction. We find that the 1D interface exciton has giant binding energy in the same order as 2D excitons in pristine monolayer TMDs although the effective radius (electron-hole separation) of interface exciton is much larger than that of 2D excitons. The binding energy, exciton radius, and optical dipole strongly depends on the band offset at the junction. The intervalley coupling induced by the electron-hole Coulomb exchange interaction and the quantum confinement effect at interfaces of a closed triangular shape are also investigated. Small triangles realize 0D quantum dot confinement of excitons, and we find a transition from nondegenerate ground state to degenerate ones when the size of the triangle varies. Our findings may facilitate the implementation of the optoelectronic devices based on the lateral heterojunction structures in monolayer semiconductors.
29 citations
TL;DR: In this article, the authors measured the dark conductivity and optical transmittance of free-standing porous silicon films of different porosities and found that with increasing porosity from 40 to 80%, the transmission spectrum shows a blue shift and activation energy of the conductivity increases from 0.3 to 1.0 eV.
Abstract: The quantum confinement effect was examined by measuring dark conductivity and optical transmittance of free-standing porous silicon films of different porosities. With increasing porosity from 40 to 80%, the transmission spectrum shows a blue shift and the activation energy of the conductivity increases from 0.3 to 1.0 eV. Using the activation energies, confinement energies are estimated with respect to the crystallite size, determined from the given porosity, and the results are compared with previous works. Good agreement is obtained.
29 citations
TL;DR: In this article, a layered perovskite (OA)2(MA)n−1PbnBr3n+1 (OA =C8H17NH3) was proposed for light emitting diodes.
Abstract: Air instability and poor exciton recombination of 3D perovskites MAPbX3 (MA = CH3NH3, X = halogens) seriously hinder their applications in light emitting diodes. Herein, we report a promising alternative to solve these two critical drawbacks. Layered perovskite OA2(MA)n−1PbnBr3n+1 (OA = C8H17NH3) has higher binding energy and is passivated by long organic chain, which can be synthesized using a facile method. By increasing the OA+ ratio in layered perovskite, strong quantum confinement effect and obvious features of exciton were observed in photoluminescence and UV-Vis absorption spectra. Notably, the photoluminescence quantum yield (PLQY) of (OA)2(MA)2Pb3Br10 (n = 3 layered perovskite) can be up to 67.3% due to the enhanced exciton recombination, significantly higher than its 3D counterpart. Moreover, layered perovskite exhibits promoted stability in air than that of the 3D perovskite. The layered perovskite (OA)2(MA)2Pb3Br10-based perovskite light emitting diodes (PeLEDs) with a maximum current efficiency, a maximum power efficiency and the external quantum efficiency (EQE) of 1.43 cd A−1, 0.89 lm W−1, and 0.53% was demonstrated, which can be compared with that of the best-reported perovskite quantum dots LEDs so far. The demonstration of layered perovskite renders its bright future in optoelectronic applications, such as displays and photodetections.
29 citations
TL;DR: In this paper, the exciton-longitudinal-optical-phonon (LO phonon) interaction was observed to decrease with reducing ZnO particle size to its exciton Bohr radius (aB).
Abstract: The exciton-longitudinal-optical-phonon (LO-phonon) interaction was observed to decrease with reducing ZnO particle size to its exciton Bohr radius (aB). The unapparent LO-phonon replicas of free exciton (FX) emission and the smaller FX energy difference between 13 and 300K reveal decreasing weighting of exciton-LO phonon coupling strength. The diminished Frohlich interaction mainly results from the reducing aB with size due to the quantum confinement effect that makes the exciton less polar.
29 citations
TL;DR: In this article, a single-step synthesis of stable, luminescent aqueous colloids of mercaptopropionic acid capped cadmium selenide nanoparticles of controllable size was reported.
29 citations