The highly-efficient light-emitting diodes based on transition metal dichalcogenides: from architecture to performance

Abstract

Transition metal dichalcogenides (TMDCs) with layered architecture and excellent optoelectronic properties, have been a hot spot of light-emitting diode (LED). Nowadays, the light emitting efficiency of TMDC LEDs is still...

Directly visualizing carrier transport and recombination at individual defects within 2D semiconductors

“…The unique optoelectronic properties of two-dimensional semiconductors (2DSCs), such as the transition metal dichalcogenides (TMDs), make them attractive candidates for use in a variety of electronic and photonic devices, including photovoltaic cells, [1][2][3][4][5][6][7] photodetectors, [8][9][10] and LEDs. 11,12 The inherent 2D structure of these materials allows them to be prepared as ultrathin films down to the monolayer limit, which can serve as flexible active layers with favorable optical properties as compared to the bulk material. [13][14][15][16][17][18] Unfortunately, the fabrication of efficient, practical optoelectronic devices based on 2DSCs remains difficult due to an incomplete understanding of the factors governing carrier generation, transport, and recombination in these materials.…”

Tuning exciton recombination rates in doped transition metal dichalcogenides

“…in ultra-clean 2D quantum confined systems [3], TMDs also provide new exciting solutions for optoelectronic [4], valleytronic [5] and nonlinear optical [6,7] applications. In particular, the giant enhancement of the photoluminescence (PL) quantum yield (QY) in the monolayer limit [1] holds great promise for integrated, flexible and high-speed light emitting devices [8]. In this regard, it is paramount to consider that light emission in TMDs strongly depends on intrinsic and extrinsic factors such as doping, environment, defects, strain and the photoexcited carrier density [3,9].…”

Diluted Magnetic Semiconductors Nanocrystals: Saturation and Modulation

“…These adjustments are made in the positions of absorption of Mn 2+ ions, making possible the use of the crystalline field theory (CFT) based on the crystalline field strength parameters ∆ and Racah B, both calculated with help of Tanabe-Sugano diagram (Figure 1(c)) [20]. From the OA spectra of the NCs of Zn: xMn, based on the Tanabe-Sugano diagram, the energies of the characteristic electronic transitions of Mn 2+ : 6 A 1 ( 6 S) → 4 T 1 ( 4 G) (691 nm), 6 A 1 ( 6 S) → 4 T 2 ( 4 G) (590 nm), 6 A 1 ( 6 S) → 4 T 2 ( 4 D) (482 nm), and 6 A 1 ( 6 S) → 2 E ( 2 I) (410 nm) (Figure 1b) subtly permitted by spin-orbit coupling were effectively described by the Racah B parameter (559 cm −1 ) and the crystalline field division (∆ = 5464 cm −1 ) [21,22].…”

“…These new properties are attributed to the sp-d exchange interactions that involve the d-sub-levels of transition metal (TM) ions and the sp-electrons of the conduction band and/or holes in the host semiconductor valence band [4,5]. These materials are called diluted magnetic semiconductors (DMS) and present great possibilities for technological applications such as the production of light-emitting diodes (LEDs) [6], spin transistors [7], lasers [8], supercapacitor [9], among others. DMS materials, when developed under the quantum confinement regime, form nanocrystals (NCs) with smaller dimensions than the bulk material [10].…”