Photostability and Photoinduced Processes in CuInS 2 /ZnS Quantum Dots and Their Hybrid Structures with Multilayer Graph
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PHOTONICS
Photostability and Photoinduced Processes in CuInS2/ZnS Quantum Dots and Their Hybrid Structures with Multilayer Graphene Nanoribbons I. A. Reznika, *, D. A. Kurshanova, A. Yu. Dubovika, M. A. Baranova, S. A. Moshkalevb, A. O. Orlovaa, and A. V. Baranova a ITMO
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University, St. Petersburg, 197101 Russia State University of Campinas (Unicamp), SP 13083-970 Campinas, Brazil * е-mail: [email protected] Received June 28, 2020; revised June 28, 2020; accepted July 16, 2020
Abstract—The photostability of the luminescent properties of CuInS2/ZnS quantum dots (CIS/ZnS QDs) as a monolayer on a dielectric substrate and as part of a hybrid structure with multilayer graphene nanoribbons (ML GNRs) has been studied. Analysis of the luminescence kinetics of quantum dots has revealed the presence of three main components of luminescence attenuation, characterized by times of the order of 20, 100, and 300 ns. It has been shown that the efficiency of the interaction between CIS/ZnS quantum dots and multilayer graphene nanoribbons has a dependence on the number of graphene monolayers similar to that of CdSe quantum dots. The photostability of CIS/ZnS QDs on a dielectric substrate and in structures with multilayer graphene nanoribbons has been estimated, which allowed us to estimate the energy/charge transfer rates from QDs to multilayer graphene nanoribbons as 106–107 s–1. Keywords: CuInS2/ZnS quantum dots, multilayer graphene nanoribbons, defective luminescence, energy/charge transfer, photoinduced processes DOI: 10.1134/S0030400X20110223
1. INTRODUCTION The quantum dots based on triple compounds of the elements of I–III–VI groups such as AgInS2 (AIS) and CuInS2 (CIS), as well as QDs with ZnS–AIS/ZnS and CIS/ZnS shells are intensively studied as a nontoxic alternative to QDs based on cadmium selenide and cadmium telluride for use in photovoltaics and biomedicine [1–4]. The first works concerning the synthesis of quantum dots data appeared about ten years ago [5]. The CIS compound is known as a direct semiconductor with a band gap of 1.5 eV (~830 nm). In QDs, because of the quantum-dimensional effect, the width of the band gap depends on its size, as well as on the elemental composition of the QD and ligands on its surface [5, 6]. Therefore, both the long-wave absorption boundary and the luminescence peak of CIS QDs can be changed in the range from the visible to the near-IR range [7, 8]. To increase the stability of the optical parameters of CIS QDs and the quantum yield of luminescence, CIS nanocrystals are usually coated with a ZnS shell [9]. CIS/ZnS along with AIS/ZnS quantum dots can be used in Biomedicine as donors for transferring photoexcitation energy to luminescent markers or as luminescent markers themselves [10,
11]. The possibilities of their use as a phosphor in new generations of cadmium-free LEDs based on quantum dots are being considered [12, 13]. In both cases, the information about the photostability of CIS/ZnS quantum dots in hybrid structures with dielectric, such as glass or polymer, and cond
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