No abstract

CuIn(1-x)GaxSe2 (CIGS) is one of the most promising thin film photovoltaic technologies for commercial application. Flexible Polyimide (PI) substrate based CIGS solar cells have lots of advantages such as lightness, flexibility, shatter resistance, and so on. However, due to the low glass transition temperature of the commercial PI substrate, the performances of flexible CIGS solar cell and module are much lower than that of CIGS solar cell and module on rigid glass substrate. In this study, we report a two-step process for preparation of PI with high decomposition temperature (Td) and 5% weight loss temperature (Td,5) of 551 and 596 °C, respectively. In addition, Mo films were deposited on the high temperature PI substrate by magnetron sputtering. The effect of deposition pressure on the growth rate, resistivity, microstructure, and surface morphologies of the magnetron sputtering deposited Mo film were investigated. We have shown the Mo coated high temperature PI films has the potential for substrate application in high efficiency flexible CIGS solar cell fabrication.

Cyanate ester (CE) resins with higher heat resistance, lower coefficients of thermal expansion (CTEs), and lower water absorption ratios are highly desired in printed circuit boards (PCBs). In this work, a CE was modified by copolymerization with a long-chain thioether bismaleimide (SBMI) to form a thioetherimide-modified CE (SBT). The results indicated that SBT had a wider processing window and better processing properties than a common bismaleimide-modified CE resin (MBMI). After molding with a glass fiber cloth, the composites (GSBT) exhibited moisture adsorption in the range of 1.4%–2.0%, high tensile strength in the range of 311–439 MPa, good mechanical retention of 70%–85% even at 200 °C, and good dimension stability, with coefficients of thermal expansion in the range of 17.3–18.6 (×10−6 m/°C). Such GSBT composites with superior properties would be good candidates for PCB applications.

Hydrothermal reaction of 4-cyanobenzoic acid with NaN 3 in the presence of Ln(NO 3 ) 3 Á 6H 2 O produced two lanthanide complexes, [LnL(HL)(H 2 O) 5 ] [Ln ¼ Eu (1) and Tb (2)] (H 2 L ¼ 4-(1H-tetrazol-5-yl)benzoic acid). Both compounds were structurally characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Complexes 1 and 2 are isostructural and display 3-D supramolecular frameworks. Solid-state properties such as thermal behaviors and photoluminescence for these crystalline materials were also investigated.

In order to match the fabrication process of flexible Copper-Indium-Gallium-Selenide (CIGS) solar cell, a series of polyimides (PIs) with high initial decomposition temperatures (Td) were prepared from 6,4′-diamino-2′-trifluoromethyl-2-phenylbenzimidazole (DATFPBI), p-phenylenediamine (p-PPD), and S-type biphenyl dianhydride (s-BPDA) using a sequential copolymerization, casting, and thermal imidization process. The physical properties of the PIs were found to be effectively modified by adjusting both the ratio of the rigid momomers and the thermal imidization process. With the introduction of DATFPBI, the polymers showed significant improvements in thermal stability, thermal expansion, moisture absorption and mechanical properties. PIPBId, one of the synthesized PI film, exhibited an excellent comprehensive performance: a glass transition temperature of 368°C, a tensile modulus of 6.8 GPa, a linar coefficient thermal expansion (CTE) of 16.8 ppm/K, and a moisture absorption of 1.42%. Furthermore, Td of this thin film was up to 524°C,which indicated that the PIPBId film is a competitive candidate as the flexible substrate for CIGS, Copper-Zinc-Tin-Sulphide (CZTS) solar cell and flexible printed circuit boards (FPCB) where high process temperature is necessary.