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As a first step toward the realization of high-efficiency Cu2(Sn1-xGex)S3 (CTGS) solar cells, this study investigates the effects of the growth process, focusing on the crystalline structure and morphology of CTGS films formed via different growth processes. These processes include the sulfurization of the Ge/Cu/Sn-S precursor; sulfurization of Cu2SnS3 (CTS) with S and germanium sulfide (GeS) vapor; and co-evaporation of Cu, Sn, Ge, and S. The CTGS films obtained by sulfurization of the Ge/Cu/Sn-S precursor consistently exhibited the largest grain sizes. However, the surface roughness of CTGS films increased with increasing x ratio. Conversely, the CTGS films obtained by the re-sulfurization of CTS films previously formed in S and GeS mixed vapor exhibited both a large grain size and flat surface roughness, rendering them suitable for forming the p-n interface in a solar cell. Therefore, the re-sulfurization of CTS films previously formed in S and GeS mixed vapor is key for achieving high-efficiency solar cells. [ABSTRACT FROM AUTHOR]

Ag8SnS6 (ATS) has been reported to have a band gap of 1.33 eV and is expected to be a suitable material for the light-absorbing layers of compound thin-film solar cells. However, studies on solar cells that use ATS are currently lacking. The objective of this study is to obtain high-quality ATS thin films for the realization of compound thin-film solar cells using vacuum deposition and sulfide annealing. First, glass/SnS/Ag stacked precursors are prepared by vacuum deposition. Subsequently, they are converted to the ATS phase via sulfide annealing, and various process conditions, namely, annealing time, annealing temperature, and number of steps, are studied. By setting the heat treatment temperature at 550 °C and the heat treatment time at 60 min, a high-quality ATS thin film could be obtained. Multi-step heat treatment also produces thin films with nearly no segregation or voids. [ABSTRACT FROM AUTHOR]

To improve the quality and obtain single-phase monoclinic Cu2SnS3 (CTS) thin films, precursors, which were deposited by a non-vacuum dual-source fine-channel mist chemical vapor deposition (CVD) process, were annealed by covering them with a soda lime glass (SLG) substrate or other precursors. After annealing with a cover, the annealed precursor showed X-ray diffraction (XRD) peaks attributable only to monoclinic CTS; however, the chemical composition of the annealed precursor covered by other types of precursors deviated from the stoichiometry. The SLG substrate was found to be suitable for the cover, and the annealing temperature dependence of cover annealing on the SLG substrate was investigated. When annealing the CTS thin film at 550 °C, only a single-phase monoclinic CTS was found in the XRD and Raman measurements. The bandgap of the CTS thin film was estimated to be approximately 0.91 eV from the α h ν 2 plots. Thus, the deposition results showed that a Cu-poor CTS thin film suitable for high-efficiency solar cells can be prepared using a non-vacuum process without the sulfurization treatment. [ABSTRACT FROM AUTHOR]

In this work, a comprehensive study on the influences of the various synthesizing parameters of monoclinic Cu2SnS3 using the RF sputtering method, followed by the sulfurization process, is investigated. In particular, the impact of sputtering power and pressure on multi-material target Cu–Sn (compositional ratio Cu:Sn of 52:48%) was examined. All samples exhibited a monoclinic structure with similar split bandgaps around 0.9 eV. Increasing sputtering power showed direct effects on the sputtered Cu/Sn atoms ratio and the secondary phases obtained. The increase of sputtering pressure causes gas droplets and blistering on the film surfaces. The effects of changing the sulfurization temperature and the sulfur powder amount were also studied. The increase in the sulfurization temperature reduces the surface roughness, increases film crystallinity, and minimizes Cu-based secondary phases. The sulfur amount used during the sulfurization process showed a vital impact on film formation. Using a small amount of sulfur produced a partially sulfurized film that exhibited a poor performance solar cell. A power conversion efficiency of 1.94% is achieved with the optimized condition for the bare Cu2SnS3 without doping or heat treatment for the fabricated cell. [ABSTRACT FROM AUTHOR]

Simple Summary: Carbon ion radiotherapy is an emerging cancer treatment modality that has a greater therapeutic window than conventional photon radiotherapy. To maximize the efficacy of this extremely scarce medical resource, it is important to identify predictive biomarkers of higher carbon ion relative biological effectiveness (RBE) over photons. Here we show that the carbon ion RBE in human cancer cells correlates with the cellular uptake of 64Cu(II)-diacetyl-bis(N4-methylthiosemicarbazone) (64Cu-ATSM), a potential radioligand that reflects an over-reduced intracellular environment. High RBE/64Cu-ATSM cells show greater steady-state levels of antioxidant proteins and increased capacity to scavenge reactive oxygen species in response to X-rays than low RBE/64Cu-ATSM counterparts. These data suggest that the cellular antioxidant activity is a possible determinant of carbon ion RBE predictable by 64Cu-ATSM uptake. Carbon ion radiotherapy is an emerging cancer treatment modality that has a greater therapeutic window than conventional photon radiotherapy. To maximize the efficacy of this extremely scarce medical resource, it is important to identify predictive biomarkers of higher carbon ion relative biological effectiveness (RBE) over photons. We addressed this issue by focusing on cellular antioxidant capacity and investigated 64Cu(II)-diacetyl-bis(N4-methylthiosemicarbazone) (64Cu-ATSM), a potential radioligand that reflects an over-reduced intracellular environment. We found that the carbon ion RBE correlated with 64Cu-ATSM uptake both in vitro and in vivo. High RBE/64Cu-ATSM cells showed greater steady-state levels of antioxidant proteins and increased capacity to scavenge reactive oxygen species in response to X-rays than low RBE/64Cu-ATSM counterparts; this upregulation of antioxidant systems was associated with downregulation of TCA cycle intermediates. Furthermore, inhibition of nuclear factor erythroid 2-related factor 2 (Nrf2) sensitized high RBE/64Cu-ATSM cells to X-rays, thereby reducing RBE values to levels comparable to those in low RBE/64Cu-ATSM cells. These data suggest that the cellular activity of Nrf2-driven antioxidant systems is a possible determinant of carbon ion RBE predictable by 64Cu-ATSM uptake. These new findings highlight the potential clinical utility of 64Cu-ATSM imaging to identify high RBE tumors that will benefit from carbon ion radiotherapy. [ABSTRACT FROM AUTHOR]