Seed-mediated growth synthesis and tunable narrow-band luminescence of quaternary Ag–In–Ga–S alloyed nanocrystals

Abstract

Narrow-band luminescence was observed from Ag–In–Ga–S alloyed nanocrystals were synthesized through a seed-mediated growth and cation exchange strategy, which was originated from the recombination of the conduction band edge to silver vacancy states.

One-Pot Synthesis of Color-Tunable Narrow-Bandwidth Ag–In–Ga–Zn–S Semiconductor Nanocrystals for Quantum-Dot Light-Emitting Diodes

“…The formation of numerous transposition defects serving as donor and acceptor levels leads to the emission of DAP recombination, thus broadening the fwhm. When reducing the content of Ga precursors, the PL peak extended a red shift, a broadening fwhm (Figure S4a), and a higher DAP component (Figure S4b, Table S4), confirming the significance of Ga 3+ in narrowing the PL peak, which is in good accordance with previously reported work …”

“…These results indicate that the Ga ion is more likely to diffuse into the interior of AIGZS NCs, thus passivating interior defects and producing more Ag vacancies. The increase of Ag vacancies has been shown to benefit the band-to-hole emission, resulting in narrow-bandwidth emission. ,, Hence, all of these results indicate that the proper regulation of the In/Ga ratios and the presence of Zn are crucial for achieving color-tunable narrow-bandwidth AIGZS NCs.…”

“…When reducing the content of Ga precursors, the PL peak extended a red shift, a broadening fwhm (Figure S4a), and a higher DAP component (Figure S4b, Table S4), confirming the significance of Ga 3+ in narrowing the PL peak, which is in good accordance with previously reported work. 46 The corresponding X-ray diffraction (XRD) patterns of AIGZS NCs at various reaction times are presented in Figure S5. Initially, the In, Zn, and Ga precursors did not participate in the reaction; thus, the diffraction peak of the NCs corresponds solely to the Ag 2 S diffraction peak at 0 min.…”

“…Notably, the decay time of carriers trapped by donors and surface defects in the 50 min NCs are slower than that of 10 min NCs, indicating that the diffusion of Ga 3+ can passivate both intrinsic and surface defects. 46 The passivation of intrinsic defects served as donor level would diminish the contribution of DAP radiation recombination, while the surface defect passivation would reduce the contribution of nonradiative recombination, thus enhancing the PLQY of NCs (Figure 3f). Hence, the passivation effect of Ga 3+ is a crucial factor in achieving narrow-bandwidth emission and enhanced PLQY.…”

“…The second component (hundreds of picoseconds) can be attributed to carrier trapping by deep level trap states (D 2 ), which may be In–Ag (In Ag ) or Ga–Ag (Ga Ag ) substitution defects, − and the third component (sub-10 ns) can be attributed to carrier trapping by surface defects (D s ), which is correlated with the fitting results of time-resolved PL lifetime. Notably, the decay time of carriers trapped by donors and surface defects in the 50 min NCs are slower than that of 10 min NCs, indicating that the diffusion of Ga 3+ can passivate both intrinsic and surface defects . The passivation of intrinsic defects served as donor level would diminish the contribution of DAP radiation recombination, while the surface defect passivation would reduce the contribution of nonradiative recombination, thus enhancing the PLQY of NCs (Figure f).…”