Colloidal CuInSe₂ Nanocrystals in the Quantum Confinement Regime: Synthesis, Optical Properties, and Electroluminescence

Abstract

Photoluminescent, near-stoichiometric colloidal CuInSe2 nanocrystals are synthesized in large batches and with good colloidal quality. An organometallic method is used with a moderate reaction temperature (≤200 °C) to produce CuInSe2 nanocrystals with size-tunable photoluminescence spectra ranging from ∼600 to ∼850 nm. Two-dimensional photoluminescence excitation–emission maps are reported for the CuInSe2 nanocrystals, highlighting the size-tunable excitonic features. Type I heterostructured CuInSe2/ZnS nanocrystals are prepared and purified. They are found to have absolute photoluminescence quantum yields up to ∼26%. The potential to use CuInSe2/ZnS core/shell nanocrystals as a potential low toxicity active layer in light-emitting diodes is demonstrated by fabricating electroluminescent devices.

Direct Femtosecond Observation of Charge Carrier Recombination in Ternary Semiconductor Nanocrystals: The Effect of Composition and Shelling

“…For shelling, a modified literature method was followed. 43 In a typical procedure, a stock solution of 0.08 mmol of zinc(II) stearate (Zn(St) 2 , 0.05 g) dissolved in 0.4 mL of DDT and 0.5 mL of 1-octadecene (ODE) was dropwise added at 190°C to the purified nanocrystals dispersed in 0.5 g of octadecylamine (ODA) and 8 mL of ODE. The reaction was then annealed for 20 min.…”

“…CISe nanocrystals were prepared following a modified literature method. 43 In a typical procedure, 0.1 mmol of copper(I) acetate (Cu(OAc), 0.012 g) and 0.1 mmol of indium(III) acetate (In(OAc) 3 , 0.030 g) were taken in a three-neck flask along with 1 mL of DDT and 7 mL of ODE. The reaction mixture was degassed by purging with nitrogen for 15 min.…”

Highly conductive CuInSe2 nanocrystals with inorganic surface ligands

“…One of their main advantages is the direct control of their absorption spectrum via quantum confinement by tuning the NCs' diameter. To give an example, the band gap of CuInSe 2 (CIS) NCs can be tuned from the bulk value of 1.0 eV to the "ideal" value for a single junction solar cell of around 1.5 eV by decreasing their size from around 15 nme3 nm [1]. To the contrary, in thin (which means here: few micrometers thick) film solar cells based on CIS, the band gap is adjusted by alloying with gallium, yielding CuIn x Ga 1Àx S 2 nanocrystals (abbreviated as CIGS) [2].…”

Near-infrared emitting AgInTe2 and Zn-Ag-In-Te colloidal nanocrystals

“…Although NCs possess interesting properties such as a broad absorption bandwidth and tuneable emission wavelengths, most of them are based on toxic elements such as cadmium, lead, mercury or arsenic, and are hence limited in their industrial use [4][5][6][7]. More recently, NCs based on less toxic elements have also been developed [7][8][9][10][11][12]. I(Ag,Cu)-III(In,Ga)-VI(S,Se,Te) 2 compounds have been widely studied as bulk materials, principally for their successful use in photovoltaic devices [13].…”

“…I(Ag,Cu)-III(In,Ga)-VI(S,Se,Te) 2 compounds have been widely studied as bulk materials, principally for their successful use in photovoltaic devices [13]. This has motivated research on nanocrystalline versions in order to generate tuneable electronic and optical properties, especially in the biologically and technologically important near-infrared range of the spectrum [4,[8][9][10].…”