Fully Solution‐Processed Conductive Films Based on Colloidal Copper Selenide Nanosheets for Flexible Electronics

Abstract

A novel colloidal synthesis of copper selenide nanosheets (NSs) with lateral dimensions of up to 3 μm is developed. This material is used for the fabrication of flexible conductive films prepared via simple drop‐casting of the NS dispersions without any additional treatment. The electrical performance of these coatings is benchmarked against copper selenide spherical nanocrystals (SNCs) in order to demonstrate the advantage of 2D morphology of the NSs for flexible electronics. In this contest, Cu2−xSe SNC films exhibit higher conductivity but lower reproducibility due to the formation of cracks leading to discontinuous films. Furthermore, the electrical properties of the films deposited on different flexible substrates following their bending, stretching and folding are studied. A comparison of Cu2−xSe SNC and CuSe NS films reveals an increased stability of the CuSe NS films under mechanical stress applied to the samples and their improved long‐term stability in air.

Plasmonic doped semiconductor nanocrystals: Properties, fabrication, applications and perspectives

“…For example, how does the carrier damping change when moving from the copper vacant copper chalcogenides (Cu 2-x E, with E=S, Se, Te) to the limit case of CuE composition? Initial works attested a purely metallic character to CuE , while the copper vacant one appears to suffer from additional damping or carrier localization due to vacancy formation [156,184,305]. The resulting dielectric functions obtained by band structure calculations of covellite CuS shows remarkable agreement with the experimental optical spectra [358].…”

Highly Conductive Copper Selenide Nanocrystal Thin Films for Advanced Electronics

“…This value of conductivity is 1 order of magnitude less than the expected metal–insulator transition conductivity, which suggests that all the samples investigated here are in the dielectric regime. We note that conductivity values reported for Cu 2– x Se NC films span a very broad range from 10 –9 S cm –1 for untreated oleic acid-capped NCs through 10 –6 S cm –1 for the same particles treated with mercapto­propionic acid to 25 S cm –1 for a few micrometer thick films made of highly copper-deficient NCs . Such dramatic difference in values can be explained not only by different measurement techniques, different film thicknesses, different surface treatment of the NCs, and different film processing but also by different values of x , i.e., different concentrations of Cu vacancies in the particles, which in turn determine the charge concentration in the NCs.…”

Structural and Optoelectronic Properties of MoO3/CuSe Interfaces

“…As a result of changing the substrate, the maximum peak shifts toward lower angle indicating the presence of deformation in CuSe. The deformation may be attributed to the morphology that consists of overlapping between well oriented crystallites of CuSe and random ones of MoO 3 at the MoO 3 /CuSe interface . The calculated structural parameters presented by the crystallite size ( D ), microstrain (), and dislocation density () using the previously published equations are also shown in Table .…”