Self-assembled lamellar MoS ₂ , SnS ₂ and SiO ₂ semiconducting polymer nanocomposites

Abstract

Lamellar nanocomposites based on semiconducting polymers incorporated into layered inorganic matrices are prepared by the co-assembly of organic and inorganic precursors. Semiconducting polymer-incorporated silica is prepared by introducing the semiconducting polymers into a tetrahydrofuran (THF)/water homogeneous sol solution containing silica precursor species and a surface-active agent. Semiconducting polymer-incorporated MoS 2 and SnS 2 are prepared by Li intercalation into the inorganic compound, exfoliation and restack in the presence of the semiconducting polymer. All lamellar nanocomposite films are organized in domains aligned parallel to the substrate surface plane. The incorporated polymers maintain their semiconducting properties, as evident from their optical absorption and photoluminescence spectra. The optoelectronic properties of the nanocomposites depend on the properties of both the inorganic host and the incorporated guest polymer as demonstrated by integrating the nanocomposite films into light-emitting diodes. Devices based on polymer-incorporated silica and polymer-incorporated MoS 2 show no diode behaviour and no light emission due to the insulating and metallic properties of the silica and MoS 2 hosts. In contrast, diode performance and electroluminescence are obtained from devices based on semiconducting polymer-incorporated semiconducting SnS 2 , demonstrating that judicious selection of the composite components in combination with the optimization of material synthesis conditions allows new hierarchical structures to be tailored for electronic and optoelectronic applications.

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

“…The direct bandgaps of monolayer semiconducting TMDCs make them ideal candidates for the active light-emitting layer in future flexible optoelectronics, unlike graphene, which lacks a bandgap and requires chemical treatments to induce local bandgaps that photoluminesce 150,151 . Examples of electroluminescence in TMDCs include MoS 2 emitting light by electrical excitation through Au nano-contacts 152 , and electroluminescence from SnS 2 exfoliated from lithium intercalation and incorporated into a composite polymer matrix 56 . Photoluminescence is seen in monolayer MoS 2 , which has a direct bandgap, and the quantum yield of the monolayer photoluminescence is much higher than for bilayer and bulk MoS 2 (refs 32, 49).…”

“…Annealing at 300 °C can cause a phase change from 1T-MoS 2 to 2H-MoS 2 , restoring the Mo atom coordination, and restoring the semiconducting bandgap of the pristine material, as evidenced by the re-emergence of bandgap photoluminescence 49 . Lithium-based chemical exfoliation has been demonstrated 55,56 for TMDCs such as MoS 2 , WS 2 , MoSe 2 and SnS 2 .…”

Enhanced and tunable photoluminescence of polyphenylenevinylenes confined in nanocomposite films

“…The observed blue shifts in the PL spectra of CP/O300 correspond to isolation of CP macromolecules, assuming that the excitons cannot migrate to the regions of polymer chains with a lower energy. This peculiarity is an inherent characteristic of the hybrid nanocomposites based on CP and mesoporous silica or layered inorganic matrices, which were reported in the previous literature [ 13 - 19 , 21 , 24 - 26 ].…”

Two-Dimensional Electronics and Optoelectronics

“…One of the earliest light emission studies on TMDCs was one in which MoS 2 /Au nano-contacts were stimulated by scanning tunneling microscopy (STM) [200]. EL behavior was also found from exfoliated SnS 2 incorporated into a composite polymer semiconductor, but MoS 2 resulted in no light emission [201]. The result of EL in MoS 2 was reconfirmed by a monolayer MoS 2 FET, shown in Figure 14.…”