Heavy-Metal-Free Solution-Processed Nanoparticle-Based Photodetectors: Doping of Intrinsic Vacancies Enables Engineering of Sensitivity and Speed

Abstract

Photodetection in semiconductors enables digital imaging, spectroscopy, and optical communications. Integration of solution-processed light-sensing materials with a range of substrates offers access to new spectral regimes, the prospect of enhanced sensitivity, and compatibility with flexible electronics. Photoconductive photodetectors based on solution-cast nanocrystals have shown tremendous progress in recent years; however, high-performance reports to date have employed Pb- and Cd-containing materials. Here we report a high-sensitivity (photon-to-electron gain >40), high-speed (video-frame-rate-compatible) photoconductive photodetector based on In(2)S(3). Only by decreasing the energetic depth of hole traps associated with intrinsic vacancies in beta-phase In(2)S(3) were we able to achieve this needed combination of sensitivity and speed. Our incorporation of Cu(+) cations into beta-In(2)S(3)'s spinel vacancies that led to acceptable temporal response in the devices showcases the practicality of incorporating dopants into nanoparticles. The devices are stable in air and under heating to 215 degrees C, advantages rooted in the reliance on the stable inclusion of dopants into available sites instead of surface oxide species.

Direct Assembly of Photoresponsive C60−Gold Nanoparticle Hybrid Films

“…Some of the possible charge-trapping mechanisms that are known include conversion of free charges into immobile bipolarons, stabilization by dipoles in dielectric layers, charge migration into dielectric layers, and chemical reactions with impurities (22). The current decrease upon exposure to UV light is quite unique considering that the current increase generally takes place for other photodetector systems by UV illumination (1)(2)(3)(4)(5)(6). The detailed mechanism of charge trapping that occurs for this hybrid film will be a focal point of future studies.…”

Template Synthesis of CuInS2 Nanocrystals from In2S3 Nanoplates and Their Application as Counter Electrodes in Dye-Sensitized Solar Cells

“…[18][19][20][21][22][23] Because the electronic structure of these materials strongly correlate with the [Cu]/[In] ratios, there is a great need to precisely control their size, shape, surface and compositions. 3,19,24,25 Although great success has been made in synthesis of ternary and quaternary NCs, providing several routes including thermal decomposition of single precursors, [26][27][28][29][30] solvothermal synthesis approach, [31][32][33] hot-injection 4,5,[34][35][36] and non-injection methods, 7, 37-41 the different reactivity of metallic cation precursors often leads to a poor stoichiometric control and the formation of intermediate products such as biphasic nanomaterials and heterostructures. [42][43][44][45] To overcome such drawbacks of the composition control, template synthesis through cation exchange 46 has been gaining popularity, and allowed for fabrication of ternary and quaternary NCs (such as CuInS 2 , CuInSe 2 , AgInSe 2 , CuIn x Ga 1-x S, Cu 2 ZnSnS 4 ) from respective binary NCs (such as Cu 2-x S, Cu 2-x Se, Ag 2 Se).…”

Dramatic Enhancement in Photoresponse of β-In2S3 through Suppression of Dark Conductivity by Synthetic Control of Defect-Induced Carrier Compensation

“…1,[3][4][5][6][7] It has also been synthesized in various morphologies such as nanotubes, nanowires, nanorod arrays, nanosheets, microflowers, nanoplates, single crystals and thin films by using several methods. [8][9][10][11][12][13][14] In the context of the present work which deals with the study of photoresponse in β-In 2 S 3 , only a very few nanostructures and morphologies of this material have been utilized thus far [11][12][13]15 most possibly because achieving strong attachment of In 2 S 3 nanostructure of well defined morphology on a conducting substrate is a formidable challenge. 16,17 Towards this end hydrothermal synthesis offers distinct advantage over the other methods, because it not only renders the desired morphologies of inorganic materials on a substrate in a single step, but in view of the specific high pressure (superheating) growth character adherent films of high crystalline quality can be grown fairly easily.…”