One‐Pot Exfoliation of Graphitic C₃N₄ Quantum Dots for Blue QLEDs by Methylamine Intercalation

Abstract

Here, a simplified synthesis of graphitic carbon nitride quantum dots (g‐C3N4‐QDs) with improved solution and electroluminescent properties using a one‐pot methylamine intercalation–stripping method (OMIM) to hydrothermally exfoliate QDs from bulk graphitic carbon nitride (g‐C3N4) is presented. The quantum dots synthesized by this method retain the blue photoluminescence with extremely high fluorescent quantum yield (47.0%). As compared to previously reported quantum dots, the g‐C3N4‐QDs synthesized herein have lower polydispersity and improved solution stability due to high absolute zeta‐potential (−41.23 mV), which combine to create a much more tractable material for solution processed thin film fabrication. Spin coating of these QDs yields uniform films with full coverage and low surface roughness ideal for quantum dot light‐emitting diode (QLED) fabrication. When incorporated into a functional QLED with OMIM g‐C3N4‐QDs as the emitting layer, the LED demonstrates ≈60× higher luminance (605 vs 11 Cd m−2) at lower operating voltage (9 vs 21 V), as compared to the previously reported first generation g‐C3N4 QLEDs, though further work is needed to improve device stability.

Rational Design of MoS2/C3N4 Hybrid Aerogel with Abundant Exposed Edges for Highly Sensitive NO2 Detection at Room Temperature

“…Similarly, the (002) peak of the C 3 N 4 NSs in the composites has shifted from 27.53 to 27.75° and is assigned to the decrease in the interplanar distance from 3.23 to 3.21 Å. In addition, there were no peaks observed at lower angles, which would be assigned to the porous exfoliated morphology of C 3 N 4 NSs in all of the samples, representing the destruction of the long-range planer size of the CN layers . The peak intensity of the (002) peak of C 3 N 4 decreases with increasing concentration of the Mo precursor, indicating the surface coverage by MoS 2 NSs.…”

“…In addition, there were no peaks observed at lower angles, which would be assigned to the porous exfoliated morphology of C 3 N 4 NSs in all of the samples, representing the destruction of the long-range planer size of the CN layers. 44 The peak intensity of the (002) peak of C 3 N 4 decreases with increasing concentration of the Mo precursor, indicating the surface coverage by MoS 2 NSs. Figure 3b shows the comparative Raman spectra of the pure MoS 2 aerogel with the MSN-2 hybrid.…”

“…53 The broad bands at 3181 and 3428 cm −1 represent N−H and O−H stretching, respectively. 44,54,55 Figure 4a shows the N 2 adsorption−desorption isotherms of the samples indicating representative type IV curves with H 3 type hysteresis loops. The Brunauer−Emmett−Teller (BET) surface areas of the bare C 3 N 4 and MoS 2 are equal to 43.5 and 9.2 m 2 g −1 respectively.…”

Production of C, N Alternating 2D Materials Using Covalent Modification and Their Electroluminescence Performance

“…To our best knowledge, this is the first efficient LED based on thin C 3 N 4 emitters to date and our CE is 28 times and 180 times improvement over the previously reported C 3 N 4 ‐based LEDs. [ 58,59 ] The EL spectrum of the LEDs showed a single green emission peak at 506 nm (Figure 5f), which are different from the PL spectrum showing a shoulder peak at 460 nm. This difference could be attributed to the energy transfer of excitons to lower energy sites under an electrical field [ 60,61 ] and thus, photons with a relatively lower energy were emitted in C 3 N 4 emitters.…”

Amorphous B-doped graphitic carbon nitride quantum dots with high photoluminescence quantum yield of near 90% and their sensitive detection of Fe2+/Cd2+

“…Moreover, CNQDs consist of ordered tris-triazine moieties covalently connected by trigonal nitrogen and stacked in a graphitic fashion, which endows them with high QYs (e.g., 30%-90%) and tunable fluorescent properties [25,26]. This intrinsic characteristic of CNQDs distinguishes them from traditional fluorescent materials and indicates their prospective applications in metal ion detection [27], security ink [3], and optoelectronic devices [28][29][30]. Nevertheless, major efforts in the FDT field are so far emphasized on the crystalline CNQDs-based materials.…”