Preparation, thermal analysis, and crystal structure refinement of the quaternary alloy (CuIn)2NbTe5

The quaternary alloy (CuIn)2NbTe5 was synthesized by solid-state reaction using the melt and annealing technique. The thermal analysis shows that this compound melts at 1026 K. The present alloy is isotypic with Cu2FeIn2Se5 and crystallizes in the space group P2c (Nº 112), with unit cell parameters a = 6.1964(2) Å, c = 12.4761(4) Å, c/a = 2.01, V = 479.02(3) Å3. (CuIn)2NbTe5, belonging to the system (CuInSe2)1-x(FeSe)x with x= ⅓, is a new adamantane compound with a P-chalcopyrite structure. This structure is characterized by a double alternation of anions-cations layers according to the Te-Te : Nb-In-Nb-In : Cu-In-Cu-In : Te-Te sequence, along the 010 direction.

CIGS Photovoltaics: Reviewing a Evolving Paradigm

Copper indium selenide chalcopyrite-structure alloys with gallium (CIGS) are unique among the highest performing photovoltaic (PV) semiconductor technologies. They are structurally disordered, nonstoichiometric materials that have been engineered to achieve remarkably low bulk nonradiative recombination levels. Nevertheless, their performance can be further improved. This review adopts a fundamental thermodynamic perspective to comparatively assess the root causes of present limitations on CIGS PV performance. The topics of selectivity and passivation of contacts to CIGS and its multinary alloys are covered, highlighting pathways to maximizing the electrochemical potential between those contacts under illumination. An overview of absorber growth methods and resulting properties is also provided. We recommend that CIGS researchers consider strategies that have been successfully implemented in the more mature wafer-based GaAs and Si PV device technologies, based on the paradigm of an idealized PV device design using an isotropic absorber with minimal nonradiative recombination, maximal light trapping, and both electron-selective and hole-selective passivated contacts. We foresee that CIGS technology will reach the 25% efficiency level within the next few years through enhanced collection and reduced recombination. To significantly impact power-generation applications, cost-effective, manufacturable solutions are also essential.

The new P-chalcopyrite compound Cu2FeIn2Se5; synthesis, thermal analysis (DTA), and crystal structure analysis by X-ray powder diffraction (XRPD)

The Cu2FeIn2Se5 alloy, belonging to the system (CuInSe2)1-x(FeSe)x with x= ⅓, was synthesized by the melt and annealing technique. The differential thermal analysis (DTA) indicates that this compound melts at 1017 K. The crystal structure of this new quaternary compound was established using powder X-ray diffraction. Cation distribution analysis indicates that this material crystallizes in a P-chalcopyrite structure, space group P2c (Nº 112), with unit cell parameters a = 6.1852(2) Å, c = 12.3633(9) Å, V = 472.98(4) Å3. Cu2FeIn2Se5 is a new adamantane type compound derivative of the sphalerite structure, and consists of a three-dimensional arrangement of distorted CuSe4, FeSe4, and InSe4 tetrahedral connected by common faces.

Synthesis and Characterization of CuIn1−xGaxSe2 Semiconductor Nanocrystals

In this paper, the synthesis and characterization of CuIn1−xGaxSe2 (0 ≤ x ≤ 1) nanocrystals are reported with the influences of x value on the structural, morphological, and optical properties of the nanocrystals. The X-ray diffraction (XRD) results showed that the nanocrystals were of chalcopyrite structure with particle size in the range of 11.5–17.4 nm. Their lattice constants decreased with increasing Ga content. Thus, the x value of the CuIn1−xGaxSe2 nanocrystals was estimated by Vegard’s law. Transmission electron microscopy (TEM) analysis revealed that the average particle size of the nanocrystals agreed with the results of XRD. Well-defined lattice fringes were shown in the TEM images. An analysis of the absorption spectra indicated that the band gap energy of these CuIn1−xGaxSe2 nanocrystals was tuned from 1.11 to 1.72 eV by varying the x value from 0 to 1. The Raman spectra indicated that the A1 optical vibrational mode of the nanocrystals gradually shifted to higher wavenumber with increasing x value. A simple theoretical equation for the A1 mode frequency was proposed. The plot of this equation showed the same trend as the experimental data.

Influence of Sulfur Precursor Solutions on Crystallinity of CuInS2 Nanocrystals Fabricated with Hot-Injection Method

The hot-injection method was used for the synthesis of ternary metal chalcogenide nanocrystals (NCs) CuInS2 (CIS); this was achieved by using the metal precursors (copper iodide and indium acetate) and four different types of sulfur precursor solutions. It was discovered that CIS NCs synthesized with different sulfur precursor solutions exhibited the chalcopyrite structure with similar particle sizes of ~4.2 nm. As a comparison, CIS NCs synthesized using ODE-S precursor displayed an enhanced luminescence intensity and a long PL decay lifetime, which could be considered as an evidence of improved interior crystallinity.