Binder-Free Cu–In Alloy Nanoparticles Precursor and Their Phase Transformation to Chalcogenides for Solar Cell Applications

Abstract

A low-cost, nonvacuum fabrication route for CuInSe 2 and CuInS 2 thin films is presented. To produce these films, binder-free colloidal precursors were prepared using Cu−In intermetallic nanoparticles that were synthesized via a chemical reduction method. The Cu−In alloy precursor films were transformed to CuInSe 2 and CuInS 2 by reactive annealing in chalcogen-containing atmospheres at atmospheric pressure. The as-synthesized nanoparticles and the annealed films were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray spectrometry, electron probe X-ray microanalysis, Raman spectroscopy, and Auger electron spectroscopy depth profile measurements to elucidate the phase evolution pathway and the densification mechanism of the Cu−In−Se−S system. Solar cell devices made with CuInSe 2 and CuInS 2 absorbing layers exhibited power conversion efficiencies of 3.92% and 2.28%, respectively. A comparison of the devices suggested that the microstructure of the absorbing layer had a greater influence on the overall photovoltaic performance than the band gap energy. A diode analysis on the solar cell devices revealed that the high saturation current density and diode ideality factor caused lower open-circuit voltages than would be expected from the band gap energies. However, the diode analysis combined with the microstructural and compositional analysis offered guidance about how to improve the photovoltaic performance of these devices.

Low temperature formation of CuIn 1−x Ga x Se 2 solar cell absorbers by all printed multiple species nanoparticulate Se + Cu–In + Cu–Ga precursors

“…Absorber layers also processed from Cu-In nanoparticles by Kind et al [16] or Lim et al [17] but under Se(g) atmosphere, show a dense CISe layer on top of a porous CISe layer similar to the one presented in this work. The densification can be attributed to a permanently saturated Se atmosphere surrounding the precursor particles near the surface of the precursor.…”

“…This is attributed to the quasi-closed graphite box which reduced the evaporation rate and therefore allowed the formation of a higher amount of MoSe 2 but did not lead to grain growth in the absorber. Grain growth was not observable in this work but is reported in literature for similar precursor systems annealed in a saturated Se atmosphere [16,17].…”

“…The most prominent techniques are based on deposition of material from solution [6][7][8] or deposition of nanoparticles, while there is a difference in the type of used nanoparticles. One has to distinguish between chalcopyrite nanoparticles which consist of a well-formed Cu(In 1 − x Ga x )(Se 1 − y S y ) phase [9][10][11][12][13] and precursor nanoparticles which can be a mixture of either Cu-Se and In-Se nanoparticles [14] or metallic Cu-In nanoparticles which are selenised after deposition by annealing under highly toxic H 2 Se or selenium atmosphere [15][16][17].…”

Electronic structure and absolute band edge position of tetragonal AgInS2 photocatalyst: A hybrid density functional study

“…I-III-VI ternary semiconductor compounds, such as AgInS 2 , AgGaS 2 , AgGaSe 2 , CuInS 2 and CuGaTe 2 , have numerous applications including solar cell, photocatalysts and optoelectronic devices [1][2][3][4][5][6][7]. Among these compounds, AgInS 2 and its solid solutions have attracted more and more attention due to larger absorption coefficient in the visible light region and environmentally friendly feature [8][9][10].…”

Fabrication of high-performance CuInSe2 nanocrystals-modified TiO2 NTs for photocatalytic degradation applications

“…Very recently, I-III-IV 2 compounds, particularly CuInSe 2 NCs, as a chalcopyrite structure [26] with high absorption coefficients and good photostability [27][28][29], are regarded as the most promising light-absorbing materials [30]. Its band gap (1.04 eV) is ideally located within the solar spectrum [31].…”