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 ▲]

Silver Doped Cu2SnS3 Absorber Layers for Solar Cells Application

in IEEE Journal of Photovoltaics (2017)

Reaction chemistry of group IV containing copper chalcogenide semiconductors Cu2MX3 (M=Sn,Ge and X=S,Se)

in Journal of Alloys and Compounds (2016)

Chemical stability of the Cu2SnS3/Mo interface

Poster (2016, June)

Cu2SnS3 is an earth abundant semiconductor researched for photovoltaic applications. Due to the small energy difference in the Sn2+/4+ oxidation states and low free energy of MoS2, the Cu2SnS3/Mo ... [more ▼]

Cu2SnS3 is an earth abundant semiconductor researched for photovoltaic applications. Due to the small energy difference in the Sn2+/4+ oxidation states and low free energy of MoS2, the Cu2SnS3/Mo interface is unstable and Cu2SnS3 decomposes. The interface is stabilized by growing Cu2SnS3 on a thin MoS2 layer. Photoluminescence occurs only at the back of the Cu2SnS3 layers when grown on MoS2 and no quantifiable amounts of Cu and Sn are measured at the MoS2 substrate. The quenching of emission of Cu2SnS3 grown on Mo is due to binary sulfides formed in presence of Mo which are not formed when Cu2SnS3 is grown on MoS2. [less ▲]

Quantum efficiency measurements and modeling to monitor air annealing of Cu2SnS3 solar cells

in IEEE Journal of Photovoltaics (2016)

13.3% efficient solution deposited Cu(In,Ga)Se 2 solar cells processed with different sodium salt sources

in Progress in Photovoltaics (2015)

Optical characterization of solution based synthesis of Cu2SnS3 for photovoltaic applications

Poster (2015, April)