Biomolecular Embossing

The replica molding and embossing of DNA texture has been achieved using a conventional polyurethane mold. The final process requires no additional or separate extraction phases. The polyurethane replica is stable up to 150 °C and possesses a good longevity and a capacity to emboss a biological entity into a thermosetting plastic such as poly(ethylene terephthalate)

Biomolecular Embossing

The replica molding and embossing of DNA texture has been achieved using a conventional polyurethane mold. The final process requires no additional or separate extraction phases. The polyurethane replica is stable up to 150 °C and possesses a good longevity and a capacity to emboss a biological entity into a thermosetting plastic such as poly(ethylene terephthalate)

Biomolecular Embossing

The replica molding and embossing of DNA texture has been achieved using a conventional polyurethane mold. The final process requires no additional or separate extraction phases. The polyurethane replica is stable up to 150 °C and possesses a good longevity and a capacity to emboss a biological entity into a thermosetting plastic such as poly(ethylene terephthalate)

Biomolecular Embossing

The replica molding and embossing of DNA texture has been achieved using a conventional polyurethane mold. The final process requires no additional or separate extraction phases. The polyurethane replica is stable up to 150 °C and possesses a good longevity and a capacity to emboss a biological entity into a thermosetting plastic such as poly(ethylene terephthalate)

Biomolecular Embossing

The replica molding and embossing of DNA texture has been achieved using a conventional polyurethane mold. The final process requires no additional or separate extraction phases. The polyurethane replica is stable up to 150 °C and possesses a good longevity and a capacity to emboss a biological entity into a thermosetting plastic such as poly(ethylene terephthalate)

Biomolecular Embossing

The replica molding and embossing of DNA texture has been achieved using a conventional polyurethane mold. The final process requires no additional or separate extraction phases. The polyurethane replica is stable up to 150 °C and possesses a good longevity and a capacity to emboss a biological entity into a thermosetting plastic such as poly(ethylene terephthalate)

CuInSe₂ (CIS) Thin Film Solar Cells by Direct Coating and Selenization of Solution Precursors

CuInSe2 (CIS) absorber layer was formed by a direct nonvacuum coating and a subsequent selenization of precursor solutions of Cu(NO3)2 and InCl3 dissolved in methanol. The viscosity of precursor solutions was adjusted by adding ethyl-cellulose (EC) to be suitable for the doctor-blade coating. During the coating and drying process Cu2+ ions in the starting solution were reduced to Cu+, resulting in precursor films consisting of CuCl crystals and amorphous In compound embedded in EC matrix. Selenization of the precursor films with Se vapor at elevated temperature generated double-layered films with an upper layer of chalcopyrite CIS and a carbon residue bottom layer. Significant In loss was observed during the selenization, which was attributed to the evaporation of the In2Se binary phase, confirmed by investigating the change in the Cu/In ratio of the selenized film as a function of Se flux and substrate temperature. As a proof-of-concept, thin film solar cells were fabricated with the double-layered absorber film and the devices exhibited reproducible conversion efficiency as high as about 2%

Tailored Band Structure of Cu(In,Ga)Se₂ Thin-Film Heterojunction Solar Cells: Depth Profiling of Defects and the Work Function

An efficient carrier transport is essential for enhancing the performance of thin-film solar cells, in particular Cu­(In,Ga)­Se2 (CIGS) solar cells, because of their great sensitivities to not only the interface but also the film bulk. Conventional methods to investigate the outcoming carriers and their transport properties measure the current and voltage either under illumination or dark conditions. However, the evaluation of current and voltage changes along the cross-section of the devices presents several limitations. To mitigate this shortcoming, we prepared gently etched devices and analyzed their properties using micro-Raman scattering spectroscopy, Kelvin probe force microscopy, and photoluminescence measurements. The atomic distributions and microstructures of the devices were investigated, and the defect densities in the device bulk were determined via admittance spectroscopy. The effects of Ga grading on the charge transport at the CIGS–CdS interface were categorized into various types of band offsets, which were directly confirmed by our experiments. The results indicated that reducing open-circuit voltage loss is crucial for obtaining a higher power conversion efficiency. Although the large Ga grading in the CIGS absorber induced higher defect levels, it effectuated a smaller open-circuit voltage loss because of carrier transport enhancement at the absorber–buffer interface, resulting from the optimized conduction band offsets

Carbon-Impurity Affected Depth Elemental Distribution in Solution-Processed Inorganic Thin Films for Solar Cell Application

A common feature of the inorganic thin films including Cu­(In,Ga)­(S,Se)₂ fabricated by nonvacuum solution-based approaches is the doubled-layered structure, with a top dense inorganic film and a bottom carbon-containing residual layer. Although the latter has been considered to be the main efficiency limiting factor, (as a source of high series resistance), the exact influence of this layer is still not clear, and contradictory views are present. In this study, using a CISe as a model system, we report experimental evidence indicating that the carbon residual layer itself is electrically benign to the device performance. Conversely, carbon was found to play a significant role in determining the depth elemental distribution of final film, in which carbon selectively hinders the diffusion of Cu during selenization, resulting in significantly Cu-deficient top CISe layer while improving the film morphology. This carbon-affected compositional and morphological impact on the top CISe films is a determining factor for the device efficiency, which was supported by the finding that CISe solar cells processed from the precursor film containing intermediate amount of carbon demonstrated high efficiencies of up to 9.15% whereas the performances of the devices prepared from the precursor films with very high and very low carbon were notably poor