Comparisons of the structural and optical properties of o-AgInS2, t-AgInS2, and c-AgIn5S8 nanocrystals and their solid-solution nanocrystals with ZnS

Abstract

Cubic AgIn 5 S 8 (c-AgIn 5 S 8 ) as well as orthorhombic AgInS 2 (o-AgInS 2 ) and tetragonal AgInS 2 (t-AgInS 2 ) nanocrystal (NC) luminophores are successfully prepared by adjusting the stoichiometric [Ag] : [In] ratio at reaction temperatures ranging from 100 to 180 C. The photoluminescence (PL) quantum yield (QY) of c-AgIn 5 S 8 NCs reached 18.8%, which is much higher than that of o-AgInS 2 and t-AgInS 2 . In this study, the identification and characterization of efficient c-AgIn 5 S 8 luminophore NCs are reported for the first time. Broad PL bands, large Stokes shifts and long PL lifetimes indicate that the PL of c-AgIn 5 S 8 as well as o-AgInS 2 and t-AgInS 2 NCs can be attributed to donor-acceptor (D-A) pair recombinations. The PL peak shifts and changes in the PL intensity depending on the excitation intensity and temperature confirm that the c-AgIn 5 S 8 NCs comply with D-A pair recombinations. The PL emission of the NCs can be enhanced via a solid-solution with ZnS and the PL wavelength can be tuned by varying the stoichiometric [Ag] : [In] ratio and the preparation temperature. The best c-AgIn 5 S 8 -ZnS sample presents a PL emission in the range of 552-587 nm with a maximum QY of 61.3%. The luminous efficacy and color rendering index (CRI) of these AgIn 5 S 8 -ZnS NC-based white lightemitting diodes (LEDs) were respectively 53 lm W À1 and 74 at 3700 K under 60 mA. The development of an efficient AgIn 5 S 8 -ZnS NC to be applied as a color-converting material in white LEDs as demonstrated in this work provides the possibility of various potential applications in the fields of optic, optoelectronic and bio-related devices.

Synthesis and temporal evolution of Zn-doped AgInS2 quantum dots

“…As calculated in Table 2, the PL decay times are strongly dependent on the emission energies. Therefore, the PL decay of high-emission energies is faster than that of low-emission energies, which is in good agreement with the characteristics of the D-A pair recombinations [10].…”

“…For example, AIS nanoparticles prepared in a hot organic solution exhibited intense photoluminescence with a broad peak ascribed to donor-acceptor pair recombination. The emission peak and the quantum yield were tunable by coated with a wider band-gap semiconductor such as ZnS [10,11]. Up to now, much efforts have been invested to synthesis coreeshell nanocrystals in order to minimize the structural defects, making the crystal structure more stable to improve the quantum yield, thus to obtain high quality semiconductor nanocrystals [12,13].…”

Synthesis of AgInS2 Nanoparticles Directly in Poly (3-hexyl thiophene) (P3HT)Matrix: Photoluminescence Quenching Studies

“…Silver-indium sulfide AgInS 2 has a band gap between 1.87 and 2.03eV, which makes it as a promising material for applications in photovoltaics. AgInS 2 generally crystallize in orthorhombic phase at room temperature, however nanocrystals of other phases may be prepared using chemical routes [4]. At present, the research on hybrid solar cells is focused on (a) The development of new fabrication routes for hybrid thin films and (ii) the development of alternative inorganic electron acceptors that exhibit light harvesting properties superior to the typically used cadmium-based materials.…”

Electronic properties and third-order optical nonlinearities in tetragonal chalcopyrite AgInS2, AgInS2/ZnS and cubic spinel AgIn5S8, AgIn5S8/ZnS quantum dots

“…Because of its atomic structure implicating relatively dense electronic band location, one of the most interesting nonstoichiometric phases seems to be the AgIn 5 S 8 (c-AIS) crystallizing in a cubic spinel-type structure. Several works have already been devoted to the study of AgIn 5 S 8 crystals, 8,9 the synthesis of the quantum confined nanocrystals [10][11][12] as well as their interesting applications in the quantum dot based light emitting diodes 13 and the role of luminescence markers in bio-imaging and detection. 14 According to the studies performed by Delgado et al 15 the non-stoichiometric c-AIS crystallizes in a normal spinel structure (space group Fd% 3m (No.…”