Current Status of Bottom-Up Fabrication Approaches for Cu(In,Ga)Se2 Micro-Concentrator Solar Cells

in 17TH INTERNATIONAL CONFERENCE ON CONCENTRATOR PHOTOVOLTAIC SYSTEMS (CPV-17) (2022, September 02)

Cu(In,Ga)Se2 solar cells have reached a record efficiency of 23.35% and are established as a renewable energy technology. However, future large-scale fabrication might be hindered by the availability and ... [more ▼]

Cu(In,Ga)Se2 solar cells have reached a record efficiency of 23.35% and are established as a renewable energy technology. However, future large-scale fabrication might be hindered by the availability and high cost of raw materials. To reduce the amount of solar cell material, strong efforts have been devoted to the development of the micro-concentrator photovoltaics concept for Cu(In,Ga)Se2 thin film solar cells, which combines the well established concentrator photovoltaics (CPV) technology with the miniaturization of the solar cells. In this work, we review different bottom-up approaches for the fabrication of Cu(In,Ga)Se2 micro solar cells, that potentially allow the reduction of raw material, and we present the latest results on a magnetron sputtering based method for Cu(In,Ga)Se2 micro solar cells. [less ▲]

Passivating Surface Defects and Reducing Interface Recombination in CuInS2 Solar Cells by a Facile Solution Treatment

in Solar RRL (2021)

Continuous-wave laser annealing of metallic layers for CuInSe2 solar cell applications: effect of preheating treatment on grain growth

in RSC Advances (2020)

Chemical instability at chalcogenide surfaces impacts chalcopyrite devices well beyond the surface

in Nature Communications (2020)

Thin-film (Sb,Bi)2Se3 Semiconducting Layers with Tunable Band Gaps Below 1 eV for Photovoltaic Applications

in Physical Review Applied (2020), 14

Area-selective electrodeposition of micro islands for CuInSe2-based photovoltaics

in Results in Physics (2019), 12

Synthesis, theoretical and experimental characterisation of thin film Cu2Sn1-xGexS3 ternary alloys (x = 0 to 1): Homogeneous intermixing of Sn and Ge

in Acta Materialia (2018), 151

Cu2Sn1-xGexS3 is a p-type semiconductor alloy currently investigated for use as an absorber layer in thin film solar cells. The aim of this study is to investigate the properties of this alloy in thin ... [more ▼]

Cu2Sn1-xGexS3 is a p-type semiconductor alloy currently investigated for use as an absorber layer in thin film solar cells. The aim of this study is to investigate the properties of this alloy in thin film form in order to establish relationships between group IV composition and structural, vibrational and opto-electronic properties. Seven single phase Cu2Sn1-xGexS3 films are prepared from x ¼ 0 to 1, showing a uniform distribution of Ge and Sn laterally and in depth. The films all show a monoclinic crystal structure. The lattice parameters are extracted using Le Bail refinement and show a linear decrease with increasing Ge content. Using density-functional theory with hybrid functionals, we calculate the Raman active phonon frequencies of Cu2SnS3 and Cu2GeS3. For the alloyed compounds, we use a virtual atom approximation. The shift of the main Raman peak from x ¼ 0 to x ¼ 1 can be explained as being half due to the change in atomic masses and half being due to the different bond strength. The bandgaps of the alloys are extracted from photoluminescence measurements and increase linearly from about 0.90 to 1.56 eV with increasing Ge. The net acceptor density of all films is around 1018 cm 3. These analyses have established that the alloy forms a solid solution over the entire composition range meaning that intentional band gap grading should be possible for future absorber layers. The linear variation of the unit cell parameters and the band gap with group IV content allows composition determination by scattering or optical measurements. Further research is required to reduce the doping density by two orders of magnitude in order to improve the current collection within a solar cell device structure. [less ▲]

Sodium enhances indium-gallium interdiffusion in copper indium gallium diselenide photovoltaic absorbers

in Nature Communications (2018)

Deliberate and Accidental Gas-Phase Alkali Doping of Chalcogenide Semiconductors: Cu(In,Ga)Se2

in Scientific Reports (2017), 7

Alkali metal doping is essential to achieve highly efficient energy conversion in Cu(In,Ga)Se2 (CIGSe) solar cells. Doping is normally achieved through solid state reactions, but recent observations of ... [more ▼]

Alkali metal doping is essential to achieve highly efficient energy conversion in Cu(In,Ga)Se2 (CIGSe) solar cells. Doping is normally achieved through solid state reactions, but recent observations of gas phase alkali transport in the kesterite sulfide (Cu2ZnSnS4) system (re)open the way to a novel gas-phase doping strategy. However, the current understanding of gas-phase alkali transport is very limited. This work (i) shows that CIGSe device efficiency can be improved from 2% to 8% by gas-phase sodium incorporation alone, (ii) identifies the most likely routes for gas-phase alkali transport based on mass spectrometric studies, (iii) provides thermochemical computations to rationalize the observations and (iv) critically discusses the subject literature with the aim to better understand the chemical basis of the phenomenon. These results suggest that accidental alkali metal doping occurs all the time, that a controlled vapor pressure of alkali metal could be applied during growth to dope the semiconductor, and that it may have to be accounted for during the currently used solid state doping routes. It is concluded that alkali gas-phase transport occurs through a plurality of routes and cannot be attributed to one single source. [less ▲]

Nanometre-scale optical property fluctuations in Cu2ZnSnS4 revealed by low temperature cathodoluminescence

in Solar Energy Materials & Solar Cells (2017), 174