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Electrical and optical properties of silicon microscale wire (SiMW) solar cells were investigated. Diverse designs were applied for SiMW geometries as light absorbers. Finite-difference time-domain simulation shows a focused optical field in the wires inducing an optical absorption enhancement in SiMW solar cells. SiMW solar cells provided remarkably higher Voc values (0.597-0.61 V) than that of the planar solar cell (0.587 V). As for the electrical aspects, the position of the space charge region in a SiMW directly affects the carrier collection efficiency according to the SiMW diameter and significantly modulates the photogenerated-currents and voltages in solar cells.

Conventional Cu(In,Ga)Se (CIGS) solar cells exhibit poor spectral response due to parasitic light absorption in the window and buffer layers at the short wavelength range between 300 and 520 nm. In this study, the CdSe/CdZnS core/shell quantum dots (QDs) acting as a luminescent down-shifting (LDS) layer were inserted between the MgF antireflection coating and the window layer of the CIGS solar cell to improve light harvesting in the short wavelength range. The LDS layer absorbs photons in the short wavelength range and re-emits photons in the 609 nm range, which are transmitted through the window and buffer layer and absorbed in the CIGS layer. The average external quantum efficiency in the parasitic light absorption region (300-520 nm) was enhanced by 51%. The resulting short circuit current density of 34.04 mA/cm and power conversion efficiency of 14.29% of the CIGS solar cell with the CdSe/CdZnS QDs were improved by 4.35 and 3.85%, respectively, compared with those of the conventional solar cells without QDs.

The optically triggered data processing and storage provides an interesting arena for developing sophisticated next-generation smart windows and computation technology. So far, transparent and flexible metal oxides have shown phenomenal optoelectronic applications. In this article, we report a photomemory of In 2 O 3 thin film deposited on glass and PET substrate using a large-scale sputtering system. The electrical characterization of a device under light and dark conditions reveals vast persistent photoconductivity (PPC) at room temperature. The PPC is systematically exploited for multibit data storage by programming with photon pulse, intensity, and source-to-drain voltage. Similarly, a high degree of persistence (>10 4 s) is achieved to retain optical information. The underlying working mechanism is attributed to the trapping of photogenerated electrons by oxygen vacancies, while corresponding holes freely participate in electrical transport even after light termination. Finally, the energy band diagram is proposed using the In 2 O 3 work function (4.26 eV measured with KPFM) and bandgap. The functional use of a transparent thin film may provide a solution of the complex multilevel programming architecture. This flexible and lightweight device can be applied in smart transparent electronics, including memories, photodetectors, and solar cells.

Periodical nanocone-arrays were employed in an emitter region for high efficient Si solar cells. Conventional wet-etching process was performed to form the nanocone-arrays for a large area, which spontaneously provides the graded doping features for a selective emitter. This enables to lower the electrical contact resistance and enhances the carrier collection due to the high electric field distribution through a nanocone. Optically, the convex-shaped nanocones efficiently reduce light-reflection and the incident light is effectively focused into Si via nanocone structure, resulting in an extremely improved the carrier collection performances. This nanocone-arrayed selective emitter simultaneously satisfies optical and electrical improvement. We report the record high efficiency of 16.3% for the periodically nanoscale patterned emitter Si solar cell.

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