Annealing of sulfide stabilized colloidal semiconductor nanocrystals

Abstract

The effect of thermal annealing on layers of CuInS2 nanocrystals (NCs) stabilized with (NH4)2S was investigated using in situ transmission electron microscopy (TEM), in situ X-ray diffraction (XRD), thermogravimetric analysis combined with mass spectrometry (TGA-MS) and X-ray photoelectron spectroscopy (XPS). It is shown that these inorganic, chalcogen containing ligands inhibit NC sintering up to 450 °C in an inert atmosphere. On the other hand, sintering can be promoted by annealing in hydrogen gas. A similar behavior is found with Cu2ZnSnSe4 and CdSe NCs. We attribute the inhibited sintering to the oxidation of the S2− originally stabilizing the NCs to sulfite or sulfate moieties, where oxidation is possible either by exposure of the films to air or by thermal decomposition of residual solvent molecules present in the film under inert conditions

Tuning nanoscale morphology using mixed solvents and solvent vapor treatment for high performance polymer solar cells

“…Many strategies have been carried out for improving the morphology of the blend lms, such as the selection of solvent, 9 solvent additive, 21 using mixed solvents, 22 solvent vapor and thermal annealing treatments. [23][24][25] However, the morphology of active layer including narrow band gap polymer is hardly adjusted by thermal annealing treatment due to its poor self-packaging characteristic. 26,27 Recently, Liang et al reported an efficient method to adjust the active layer morphology by adopting mixed solvent approach.…”

Se-containing inks for the formation of CuInSe2 films without gas-phase selenization

“…To get a better overview on the crystal growth, we used the Scherrer equation to estimate the crystallite size after annealing from the width of the diffraction peaks. Table 2 summarizes the results for the three studied systems containing excess selenium and compares them to previous results obtained by simply annealing the as-synthesized CIS NCs [23]. The data clearly show the additional sintering effect imparted by selenization.…”

“…The synthesis of CuInS 2 NCs is based on a previously described literature procedure [23,24]. Cu(acac) 2 (1 mmol) and In(acac) 3 (1 mmol) are mixed together with S (2.05 mmol) and ODE (14 ml).…”

Hybrid Ligand Exchange of Cu(In,Ga)S2 Nanoparticles for Carbon Impurity Removal in Solution-Processed Photovoltaics

“…Further, during annealing or selenization, the DAS ligand could simply volatilize as ammonia and hydrogen sulfide gas. 46 A two-phase ligand exchange was employed as is common in the literature. 35 First, the nanoparticles were dispersed in nonpolar hexanes.…”