Explore the vast range of titles available.

Ternary chalcopyrite-like compound of CuSbSe 2 was found to be an excellent agent to assist the reactive sintering of CuInSe 2 (CIS) from Cu 2 Se and In 2 Se 3 at lower temperature, which is the light absorber material in the most promising thin film solar cells. With low melting point and excellent wettability, CuSbSe 2 acts as a liquid-phase sintering flux to efficaciously increase atomic diffusion rate during the sintering process, and furthermore the two raw materials provide chemical driving force. By the intentional introduction of CuSbSe 2 doping into CuInSe 2 , the well-crystallized ceramic samples can be perfectly sintered at 500 °C, without obviously scarifying light absorption at the low doping level (≤0.5 mol%). The XPS analyses were performed to determine the crystal lattice location and valence state of Sb. Similar sintering-promoting effect was also found in the CuSbSe 2 -doped Cu(In,Ga)Se 2 (CIGS) film.

Although an ideal bandgap matching with 0.96 eV and 1.62 eV for a double-junction tandem is hard to realize practically, among all mature photovoltaic systems, Cu(In,Ga)Se 2 (CIGSe) can provide the closest bandgap of 1.00 eV for the bottom sub-cell by adjusting its composition. However, pure CuInSe 2 (CISe) solar cell suffers strong interfacial carrier recombination. We hereby present approaches to introduce appropriate Ga gradients in both the back and front parts of absorber while maintaining the absorption spectrum close to CISe. With an appropriate front Ga gradient, the open circuit voltage can be enhanced by ~30 mV. With a pre-deposited CIGSe layer and a high copper excess deposition during absorber growth, the Ga diffusion can be well suppressed and a wide U-shaped Ga grading with a minimum bandgap of 1.01 eV has been created. Our optimized narrow-bandgap CIGSe solar cell has achieved a certified record PCE of 20.26%, with a record-low open circuit voltage deficit of 368 mV and a record-high contribution of 10% absolute efficiency to a four-terminal tandem. This work demonstrates the potential of controlling gallium diffusion to improve the performance of narrow bandgap CIGSe solar cells for tandem applications. Pure CuInSe 2 solar cells suffer from strong interfacial carrier recombination. Here, the authors introduce a wide U-shaped double Ga grading with a minimum bandgap of 1.01 eV and achieve certified device efficiency of 20.26%, making it highly suitable for tandem solar cell applications.

The currently most efficient polycrystalline solar cells are based on the Cu(In,Ga)Se2 compound as a light absorption layer. However, in view of new concepts of nanostructured solar cells, CuInSe2 nanostructures are of high interest. In this work, we report CuInSe2 nanodots grown through a vacuum-compatible co-evaporation growth process on an amorphous surface. The density, mean size, and peak optical emission energy of the nanodots can be controlled by changing the growth temperature. Scanning transmission electron microscopy measurements confirmed the crystallinity of the nanodots as well as chemical composition and structure compatible with tetragonal CuInSe2. Photoluminescence measurements of CdS-passivated nanodots showed that the nanodots are optoelectronically active with a broad emission extending to energies above the CuInSe2 bulk bandgap and in agreement with the distribution of sizes. A blue-shift of the luminescence is observed as the average size of the nanodots gets smaller, evidencing quantum confinement in all samples. By using simple quantum confinement calculations, we correlate the photoluminescence peak emission energy with the average size of the nanodots.

Semiconductors used in the manufacture of solar cells are the subject of extensive research. Currently, silicon is the most commonly used material for photovoltaic cells, representing more than 80% of the global production. However, due to its very energy-intensive and costly production method, other materials appear to be preferable over silicon, including the chalcopyrite-structured semiconductors of the CIS-based family (Cu(In, Ga, Al) (Se, S)2). Indeed, these compounds have bandwidths between 1 eV (CuInSe2) and 3 eV (CuAlS2), allowing them to absorb most solar radiation. Moreover, these materials are currently the ones that make it possible to achieve the highest photovoltaic conversion efficiencies from thin-film devices, particularly Cu(In, Ga)Se2, which is considered the most efficient among all drifts based on CIS. In this review, we focus on the CIGS-based solar cells by exploring the different layers and showing the recent progress and challenges.

The ability to grow perovskite solar cells in substrate configuration, where light enters the devices from the film side, allows the use of non-transparent flexible polymer and metal substrates. Furthermore, this configuration could facilitate processing directly on Cu(In,Ga)Se 2 solar cells to realize ultrahigh-efficiency polycrystalline all-thin-film tandem devices. However, the inversion of conventional superstrate architecture imposes severe constraints on device processing and limits the electronic quality of the absorber and charge selective contacts. Here we report a device architecture that allows inverted semi-transparent planar perovskite solar cells with a high open-circuit voltage of 1.116 V and substantially improved efficiency of 16.1%. The substrate configuration perovskite devices show a temperature coefficient of −0.18%  ° C −1 and promising thermal and photo-stability. Importantly, the device exhibits a high average transmittance of 80.4% between 800 and 1,200 nm, which allows us to demonstrate polycrystalline all-thin-film tandem devices with efficiencies of 22.1% and 20.9% for Cu(In,Ga)Se 2 and CuInSe 2 bottom cells, respectively. Perovskite solar cells grown in substrate configuration would open a range of applications, if various challenges could be overcome. Towards that aim, Fu  et al.  present an architecture allowing inverted semi-transparent planar perovskite solar cells with open-circuit voltage of 1.116 V and 16.1% efficiency.

Multi-junction solar cells show the highest photovoltaic energy conversion efficiencies, but the current technologies based on wafers and epitaxial growth of multiple layers are very costly. Therefore, there is a high interest in realizing multi-junction tandem devices based on cost-effective thin film technologies. While the efficiency of such devices has been limited so far because of the rather low efficiency of semitransparent wide bandgap top cells, the recent rise of wide bandgap perovskite solar cells has inspired the development of new thin film tandem solar devices. In order to realize monolithic, and therefore current-matched thin film tandem solar cells, a bottom cell with narrow bandgap (~1 eV) and high efficiency is necessary. In this work, we present Cu(In,Ga)Se 2 with a bandgap of 1.00 eV and a maximum power conversion efficiency of 16.1%. This is achieved by implementing a gallium grading towards the back contact into a CuInSe 2 base material. We show that this modification significantly improves the open circuit voltage but does not reduce the spectral response range of these devices. Therefore, efficient cells with narrow bandgap absorbers are obtained, yielding the high current density necessary for thin film multi-junction solar cells.

This paper presents a theoretical study of the structural, electronic, and elastic properties of gallium-doped CuInSe2 using the GGA exchange-correlation functional with the Hubbard correction for five Ga compositions: 0, 0.25, 0.5, 0.75, and 1. The found lattice parameters decrease with gallium composition and obey Vegard’s law. Traditional DFT calculations fail to explain the band structure of Copper Indium Gallium Selenide compounds (CIGS). The use of Hubbard corrections of d-electrons of copper, indium, gallium, and p-electrons of selenium opens the gap, showing a semiconductor’s behavior of CuInGaSe2 alloys in the range 1.04 eV to 1.88 eV, which are in good agreement with available experimental data and current theory using an expensive hybrid exchange-correlation functional. The obtained formation energies for the different gallium compositions are close to −1 eV/atom, and the phonon spectra indicate the thermodynamic stability of these alloys. The values of the elastic constant satisfy the Born elastic stability conditions, suggesting that these compounds are mechanically stable. Moreover, we compute the bulk modulus (B), shear modulus (G), Young’s modulus (E), Poisson ratio (p), Pugh’s ratio (r), and average Debye speed (v), and the Debye temperature (ΘD) with the Ga composition. There is a symmetry between our results and the experimental data, as well as earlier simulation results.

In this paper, the efficiency of a CIGS solar cell was increased in several stages. The common structure and configuration of the CIGS solar cell are the ZnO:Al/ZnO/CdS/CIGS/MO combination whose efficiency is optimized approximately 20% for CIGS with thickness of 2 µm and 17% for CIGS with thickness of 1 µm. In this article, thickness of CIGS is 1 µm and the efficiency of this type of solar cell was calculated using Atlas software of Silvaco. In the first step, by applying Zn 1− x Mg x O material with x  = 0.17 instead of ZnO material, the cell efficiency was 20.7% and then by adding GaAs as the electron reflector layer, we were able to achieve 27.1% efficiency and at the end, to increase the efficiency, one absorber layer is added under the CIGS absorber. This absorber layer is CIS (CIS is CuInSe 2 ) that made the efficiency to become 27.9%. Indeed, CIGS absorber layer is not able to absorb all photons of the sun. So, this added absorber layer is able to absorb a part of low-energy photons, which lead to increasing the efficiency of the solar cell. It should be noted that in the whole process of this article, CIGS and CIS absorber layers are p-type.

Innovations in the design of field-effect transistor (FET) devices will be the key to future application development related to ultrathin and low-power device technologies. In order to boost the current semiconductor device industry, new device architectures based on novel materials and system need to be envisioned. Here we report the fabrication of electric double layer field-effect transistors (EDL-FET) with two-dimensional (2D) layers of copper indium selenide (CuIn7Se11) as the channel material and an ionic liquid electrolyte (1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6)) as the gate terminal. We found one order of magnitude improvement in the on-off ratio, a five- to six-times increase in the field-effect mobility, and two orders of magnitude in the improvement in the subthreshold swing for ionic liquid gated devices as compared to silicon dioxide (SiO2) back gates. We also show that the performance of EDL-FETs can be enhanced by operating them under dual (top and back) gate conditions. Our investigations suggest that the performance of CuIn7Se11 FETs can be significantly improved when BMIM-PF6 is used as a top gate material (in both single and dual gate geometry) instead of the conventional dielectric layer of the SiO2 gate. These investigations show the potential of 2D material-based EDL-FETs in developing active components of future electronics needed for low-power applications.

The difficultness of Ga inclusion in conventional CuInGa plating can be solved by metal-oxide/hydroxide deposition. However, the selenization process with the oxide precursor is very difficult, because of the strong electronegativity of oxygen. In this work, we proposed a strategy of Cu(InGa)Se 2 thin films manufacture with selenization employing mixed precursor. The precursor consists of CuIn alloy and CuGa oxide/hydroxide, and deposited by electrodeposition as the sources of Cu, In and Ga. Then, the selenization process is performed in the mixed atmosphere of selenium vapor, hydrogen and argon. Meanwhile, we investigated the structural, optical and electrical properties of the prepared Cu(InGa)Se 2 thin films, and it implied both the deposition potential and the subsequent selenization time impact the structure and morphology of the thin films. The co-deposition of CuGa oxide/hydroxide improved the Ga deposition ratio, and it exhibited dendrite growth with large deposition potential. The subsequent selenization results in the transformation from the precursor to CuInSe 2 and Cu(InGa)Se 2 , as well as, the long selenization time lead to the oxygen concentration decreasing and high Ga concentration in CuInSe 2 films. In the end, with a potential of −0.5 V versus Ag/AgCl electrode, the film had a photo-generated current density of 0.05 mA/cm 2 , and the CIGS solar cell achieved a conversion efficiency of 1.85%.