Solution‐Based Processing of Optoelectronically Active Indium Selenide

Abstract

Layered indium selenide (InSe) presents unique properties for high-performance electronic and optoelectronic device applications. However, efforts to process InSe using traditional liquid phase exfoliation methods based on surfactant-assisted aqueous dispersions or organic solvents with high boiling points compromise electronic properties due to residual surface contamination and chemical degradation. Here, these limitations are overcome by utilizing a surfactant-free, low boiling point, deoxygenated cosolvent system. The resulting InSe flakes and thin films possess minimal processing residues and are structurally and chemically pristine. When employed in photodetectors, individual InSe nanosheets exhibit a maximum photoresponsivity of ≈5 × 10 A W , which is the highest value of any solution-processed monolithic semiconductor to date. Furthermore, the surfactant-free cosolvent system not only stabilizes InSe dispersions but is also amenable to the assembly of electronically percolating InSe flake arrays without posttreatment, which enables the realization of ultrahigh performance thin-film photodetectors. This surfactant-free, deoxygenated cosolvent approach can be generalized to other layered materials, thereby presenting additional opportunities for solution-processed thin-film electronic and optoelectronic technologies.

The role of traps in the photocurrent generation mechanism in thin InSe photodetectors

“…Indium selenide (InSe), an n-type semiconductor which belongs to the IIIVIA family, has recently attracted large attention because of its extraordinary charge transport properties, superior mechanical flexibility and strong light-matter interaction. [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] Various groups have reported transistors based on thin InSe fabricated on different substrates (SiO 2 /Si, hexagonal Boron Nitride (h-BN), poly(methyl methacrylate) (PMMA)) with mobility values as large as 3700 cm 2 V À1 s À1 at room temperature and B13 000 cm 2 V À1 s À1 at 4 K. 23,[25][26][27][28] The bandgap of 1.3 eV in bulk that becomes larger than 3 eV for an InSe single-layer makes this material interesting for broadband photodetection from the nearinfrared to the near ultraviolet region of the electromagnetic spectrum. [30][31][32][33][34][35][36][37][38][39][40] Various photodetectors based on thin InSe flakes (as the active channel part), including metal-semiconductor-metal (M-S-M) geometry and graphene based van der Waals heterostructures, have been reported in the literature with responsivities going from 0.035 A W À1 to ultrahigh values of B10 7 A W À1 and detectivities up to B10 15 Jones [30][31][32][33]…”

Monte Carlo Study of Electronic Transport in Monolayer InSe

“…However, in monolayer form, all three polytypes have the same crystal structure [29], which we simply call monolayer InSe. Recent developments of liquid-phase exfoliation of InSe flakes [30] and several emerging growth techniques [31] make InSe a material of interest for future complementary metal-oxide-semiconductor technology.…”

2D–Organic Hybrid Heterostructures for Optoelectronic Applications

“…LPE is a potential alternative approach for scalable production without such structural modification. In general, in LPE, a mechanical shear force is applied to bulk crystal or powder in a liquid medium via ultrasonication, shear mixing, or ball milling . Selection of a suitable solvent system is critical for exfoliating and stabilizing 2D nanosheets with the ultimate aim of producing stable 2D dispersions.…”