太阳能电池研究现状

太阳能电池研究现状

Activity and Current Status of R&D on

Space Solar Cells INTRODUCTION

The Japan Aerospace Exploration Agency (JAXA ), the former National Space Development Agency of Japan (NASDA), had concentrated solely on the development of silicon space solar cells until the year 2000. With the need for higher-efficiency solar cells in space , JAXA began developing III–V multi-junction (MJ ) space solar cells in 2001. Two types of high-efficiency triple-junction (3J) solar cells have been developed. These cells are fabricated using epitaxial wafers grown by companies in the United States and have an average efficiency of 28% or higher at the beginning-of-life (BOL).

For the newly developed 3J cells to be used for space missions, however, it was also necessary to collect radiation tolerance or end-of-life (EOL)

data. Accordingly, irradiation tests have been conducted to study radiation degradation behavior of the 3J cells using various types of accelerators in the Japan Atomic Energy Research Institute (JAERI) at Takasaki as part of JAXA–JAERI collaboration activities.A number of basic studies on component sub-cel ls in a 3J cell have continued to further improve MJ cell performance. One such study attempts to clarify the dependency of radiation degradation trends of III–V single-junction solar cells on their structure or environmental conditions to under stand the degradation mechanisms of MJ cells. A flight demonstration experiment of an InGaP/ GaAs solar cell and ground irradiation tests were completed in another study. The results will be applied to develop a solar cell device simulator, which should enable predictions of EOL performance of any MJ cell structure .

A copper indium gallium diselenide(CuInG aSe2(CIGS)) thin-film sol r cell is a promising

candidate for future thin-film space solar cells since the cells not only have the potential to achieve higher conversion efficiencies than other thin-film solar cells, but also show possess super radiaion tolerance.In addition, the CIGS thin-film solar cells have superior properties, such as low costand light weight, because the cells can be formed on polyimide or metal foil substrates. A flight demonstration experiment of the CIGS solar cells was per-formed ,and ground irradiation tests were conducted to investigate the mechanism s of the super ion radiation tolerance.

This paper describes R&D activities in Japan on space solar cells. The results of the activities are described.

III–V MULTIJUNCTION SOLAR CELL

Triple-jun ction cell development

Triple-junction cells have been developed under contracts with Sharp Corporation. These cells