Fig. 1. The temperature-dependent microstructure of AIGS QDs and corresponding PL spectra. (a, b, c) TEM, (d, f, h) HRTEM images, (e, g, i) histograms of the statistical distributions of particle sizes and corresponding (j, k, l) normalized PL spectra of the AIGS QDs synthesized at 180 °C, 220 °C and 250 °C, respectively.

Fig. 1. Schematic diagram of the size-dependent band gap and spectral correspondence based on size effect of QDs.

Fig. 2. The growth mechanism of dual-emissive AIGS QDs. (a) Schematic diagram of nucleation and growth patterns as a function of temperature. Stage Ⅰ: increased temperature induces decreased critical size and more nucleation, stage Ⅱ: higher nucleation rate at higher temperature lead to the growth of smaller crystals under the same concentration of precursor compared to lower temperature. (b) XRD patterns of the AIGS QDs synthesized at 180 °C, 220 °C and 250 °C, inserted on the upper and lower axe are the standard diffraction peaks of AgInS₂ and AgGaS₂. (c) The element ratio of the AIGS QDs synthesized at 180 °C, 220 °C and 250 °C analyzed by ICP-OES.

Fig. 3. The element distribution of typical AIGS QDs. (a) Schematic diagram structure of AIGS. (b–f) EDS element mapping of typical AIGS QDs for (c) Ag, (d) In, (e) Ga, (f) S.

Fig. 4. The optical properties of AIGS QDs with dual emission. (a) Photographs of the AIGS QDs synthesized at different temperature under room light (top) and UV irradiation (bottom). (b) Corresponding PL and UV-vis absorbance spectra were recorded with the excitation wavelength of 365 nm under different temperature.

Fig. 5. PL mechanism of dual-emissive AIGS QDs. (a) The temperature-dependent PL spectra of AIGS QDs under 370 nm laser excitation. (b) Peak position versus temperature for AIGS QDs. (c) Excitation power (370 nm)-dependent PL spectra AIGS QDs. (d) Emission intensity versus excitation power for the AIGS QDs at room temperature.

Fig. 6. WLED based on dual-emissive AIGS QDs. (a) The schematic diagram of constructing dual-emissive AIGS QD-based white light-emitting diode and the corresponding optical photograph of the white-emitting device. (b) PL spectra of the WLED and (c) corresponding CIE chromaticity coordinates under different voltage.