Photovoltaic Efficiency Enhancement of Indium-Free Wide-Bandgap Chalcopyrite Solar Cells via an Aluminum-Induced Back-Surface Field Effect.

Wide-bandgap chalcopyrite materials are attractive candidates for a wide variety of energy conversion devices such as the top cell of tandem-type photovoltaic devices and photoelectrochemical water splitting hydrogen evolution devices. Nevertheless, simultaneous realization of high open circuit voltage () and high fill factor (FF) values has been challenging, and thus, the photovoltaic performance has been limited. In this article, high and high FF values of wide-gap chalcopyrite CuGaSe thin-film solar cells are simultaneously demonstrated using an aluminum-induced back-surface field effect.

Lithium-Doping Effects in Cu(In,Ga)Se Thin-Film and Photovoltaic Properties.

The beneficial effects of heavy alkali metals such as K, Rb, and Cs in enhancing Cu(In,Ga)Se (CIGS) photovoltaic efficiencies are widely known, though the detailed mechanism is still open for discussion. In the present work, the effects of the lightest alkali metal, Li, on CIGS thin-film and device properties are focused upon and compared to the effects of heavy alkali metals. Till date, the beneficial effects of elemental Li on CuZnSnS photovoltaic devices in enhancing efficiencies have been reported.

Giant multiferroic effects in topological GeTe-SbTe superlattices.

Multiferroics, materials in which both magnetic and electric fields can induce each other, resulting in a magnetoelectric response, have been attracting increasing attention, although the induced magnetic susceptibility and dielectric constant are usually small and have typically been reported for low temperatures. The magnetoelectric response usually depends on -electrons of transition metals. Here we report that in [(GeTe)(SbTe) ] superlattice films (where and are integers) with topological phase transition, strong magnetoelectric response may be induced at temperatures above room temperature when the external fields are applied normal to the film surface.

Interfacial alkali diffusion control in chalcopyrite thin-film solar cells.

Alkali elements, specifically sodium (Na), are key materials to enhance the energy conversion efficiencies of chalcopyrite and related thin-film photovoltaic solar cells. Recently, the effect of potassium (K) has also attracted attention because elemental K has unique effects different from Na as well as a similar beneficial effect in improving device performance. In this study, the control of selective alkali K and Na diffusion into chalcopyrite thin-films from soda-lime glass substrates, which serve as the monolithic alkali source material and contain both K and Na, is demonstrated using ternary CuGaSe2.