Mono-crystalline silicon single heterojunction solar cells on flexible, ultra-thin (∼25 μm) substrates have been developed based on a kerf-less exfoliation method. Optical and electrical measurements demonstrate maintained structural integrity of these flexible substrates. Among several single heterojunction ∼25 μm thick solar cells fabricated with un-optimized processes, the highest open circuit voltage of 603 mV, short circuit current of 34.4 mA/cm2, and conversion efficiency of 14.9% are achieved separately on three different cells. Preliminary reliability test results that include thermal shock and highly accelerated stress tests are also shown to demonstrate compatibility of this technology for use in photovoltaic modules.

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A novel Fe(III) based gel was synthesized via self-assembly of Fe(III) and pyridine 2,6 dicarboxylic acid. The synthesized gel has remarkable mechanical strength as well as self sustainability. The metallogel...

Modern integrated circuits (ICs) employ a myriad of materials organized at nanoscale dimensions, and certain critical tolerances must be met for them to function. To understand departures from intended functionality, it is essential to examine ICs as manufactured so as to adjust design rules, ideally in a non-destructive way so that imaged structures can be correlated with electrical performance. Electron microscopes can do this on thin regions, or on exposed surfaces, but the required processing alters or even destroys functionality. Microscopy with multi-keV x-rays provides an alternative approach with greater penetration, but the spatial resolution of x-ray imaging lenses has not allowed one to see the required detail in the latest generation of ICs. X-ray ptychography provides a way to obtain images of ICs without lens-imposed resolution limits, with past work delivering 20–40 nm resolution on thinned ICs. We describe a simple model for estimating the required exposure, and use it to estimate the future potential for this technique. Here we show for the first time that this approach can be used to image circuit detail through an unprocessed 300 μm thick silicon wafer, with sub-20 nm detail clearly resolved after mechanical polishing to 240 μm thickness was used to eliminate image contrast caused by Si wafer surface scratches. By using continuous x-ray scanning, massively parallel computation, and a new generation of synchrotron light sources, this should enable entire non-etched ICs to be imaged to 10 nm resolution or better while maintaining their ability to function in electrical tests.

The optical absorption in 25-μm-thick, single-crystal Si foils fabricated using a novel exfoliation technique for solar cells is studied and improved in this work. Various light-trapping and optical absorption enhancement schemes implemented show that it is possible to substantially narrow the gap in optical absorption loss between the 25 μm Si foils and industry-standard 180-μm-thick Si wafer solar cells. An improvement of absorption by 58% in the near-infrared (740-1200 nm) range is observed for the 25 μm monocrystalline Si substrates with the use of antireflective coating and texturing. The back reflectance of the metal foil that provides mechanical support to the ultrathin Si semiconductor-on-metal foils is extracted to be ∼51.5%, based on the reflectance matching with the simulated escape reflectance in the sub-bandgap region. The back reflectance is enhanced to ∼58% by incorporating an intermediate silicon nitride layer on the back between the Si and the metal. The incorporation of Al as an improved metal reflector on top of the silicon nitride at the backside of the solar cell results in a 5.8 times enhancement in optical path length as a consequence of the improved effective back reflectance of ∼95%. A thin Si foil solar cell with an unoptimized amorphous Si/crystalline Si heterojunction with intrinsic-thin-layer design with implementation of such light-trapping schemes shows an efficiency of 13.28% with a short-circuit current density (JSC) of 35.97  mA/cm2, which approaches the JSC of industrial wafer-based Si solar cells.

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We report herein two multifunctional metal–organic frameworks (MOFs) that exhibit excellent mutually inclusive electrical and magnetic properties. Accordingly, two cobalt and nickel based MOFs (Co-MOF, Ni-MOF) were generated using a flexible bispyrazole based ligand and 2-sulphono terephthalic acid. The idea is to generate paramagnetic metal ion based magnetic MOFs, which can also be used to fabricate electrical devices by utilizing the immobilized free sulfonic groups and encapsulated H-bonded water clusters for active charge species generation and transportation. Further support comes from the intriguing structural features of the MOFs that include extensive H-bonded water clusters, free sulfonic acid moiety, or syn-anti bridged carboxylates, which make them highly suitable candidates for generating electrical and magnetic materials. Further complementary support for their candidature comes from the high thermal, chemical, and physical stability of the MOFs. The impedance spectroscopy data and I–V results unequivocally support the suitability of the MOFs for electronic device fabrication showing a befitting conductivity value of 1.80 × 10–4 S/m with an ideality factor of 1.06 for Ni-MOF. Interestingly, the Co-MOF shows a light-dependent behavior with conductivity values of 9.09 × 10–5 S/m (dark) and 6.31 × 10–4 S/m (light) and ideality factors of 0.78 (dark) and 0.92 (light). The MOFs, fitted with a free sulfonic acid moiety and extensive H-bonded water clusters, show high potential for proton exchange membrane fuel cells (PEMFCs) development with corroborating proton conductivity values of 1.95× 10–3 S/cm and 5.80 × 10–4 S/cm for Ni-MOF and Co-MOF, respectively, at 95% relative humidity and 85 °C. Moreover, the interesting structural aspects like syn-anti bridged carboxylates prompt us to explore the magnetic behavior of the MOFs. The Ni-MOF shows some interesting antiferromagnetic behavior. The Co-MOF reveals intriguing single molecule magnet behavior with a U eff value of 34 K and moderate relaxation time of 3.5× 10–8 s.

The present work reports anion-induced electrical device fabrication of Zn(II) metal-organic frameworks. The essence of our electronic device fabrication is to utilize the anionic species entrapped inside of the three-dimensional...