Tunable electroluminescence from polymer-passivated 3C-SiC quantum dot thin films

Abstract

Strong room-temperature photoluminescence in the wavelength range of 400-540 nm is achieved from a thin film containing polymer encapsulated 3C-SiC quantum dots (QDs). The QD surface is completely passivated by the polymer so that the QD film possesses voltage-tunable electroluminescence. The electroluminescence spectrum blue-shifts from 490 to 460 nm when the applied voltage is increased from 5 to 10 V. The tunable electroluminescence is attributed to carrier recombination in the core quantum confinement states as a result of Pool-Frenkel emission. Owing to the environmental friendliness, nontoxicity, easy fabrication, and stability, the polymer passivated 3C-SiC QD thin films have promising applications. V

Experimental evidence of α → β phase transformation in SiC quantum dots and their size-dependent luminescence

“…20 In contrast, the quantum yield of SiC QDs is much higher (17% 21 ) relative to that of bulk SiC due to the spatial confinement effect, and they show application potential in biological labeling 21,22 and solid-state lighting. 23,24 However, the luminescence behaviors of SiC QDs are complex and the underlying mechanisms remain unclear. 16 Herein, we report the direct experimental evidence of the hexagonal to cubic phase transformation in the SiC QDs at ambient temperature and pressure from microstructural and optical characterizations.…”

Microstructural and photoluminescent properties of terbium-doped SiC nanotubes prepared by sputtering using electrospun polymer templates

“…Xiao et al [13] observed strong room-temperature (RT) visible photoluminescence from their prepared thin film containing polymer encapsulated 3C-SiC quantum dots. And they found that the luminescence can be tuned by different exciting energies, which was attributed to the quantum confinement effect.…”

Core and Surface Electronic States and Phonon Modes in SiC Quantum Dots Studied by Optical Spectroscopy and Hybrid TDDFT

“…The surface of SiC accommodates diverse surface reconstruction and termination with corresponding defects such as bridge and triple-bonded C/Si dimers, which generate fruitful surface states in the band gap. − Hence, the SiC surface has attracted great interest. , As the dimension of the semiconductor SiC is reduced to the nanoscale, its surface structure becomes even more complex, the dangling bonds of the active carbon and silicon atoms of the freshly prepared SiC quantum dots (QDs) can readily be passivated by oxygen and hydrogen atoms to form quite fruitful bonding structures. − The resultant surface states in the band gap can actively participate in the photon absorption and emission processes. − The whole surface passivation layer becomes a two-dimensional quantum system, which in combination with quantum confinement − and the intentionally created interior point defects − determines the photodynamics ,− and charge transport properties of the SiC QDs. Therefore, understanding the surface structures and characteristics of the SiC QDs is critical for realizing their better applications in biological labeling, − solid-state lighting, − and quantum spintronics. − Our previous study indicates that the CO bonds on the SiC QD surface generate surface-localized orbitals and contribute to the blue fluorescence; however, the role of the silicon–oxygen bonds in fluorescence of the SiC QDs remains unclear. In contrast, wide investigations have revealed that the SiO fluorescence (590 nm, 2.1 eV) is the dominant surface-state fluorescence of the Si QDs .…”