IDEA #90YOXI Flexible CDTE solar cells

RENEWABLE ENERGY AND ENERGY CONSERVATION TECHNOLOGIES FLEXIBLE CDTE SOLAR CELLS Description High specific power is an important parameter for space solar cells. One approach to maximize the spe- cific power is to substitute glass substrate with flexible thin substrate, such as polymer foils. This provides not only considerable weight reduction, but also flexibility which gives an opportunity to adapt solar panels to any kind of shape. CdTe is the most suitable material for thin film so- lar cells (SC). Its band gap energy of 1.45 eV ensures an optimum adoption to the solar spectrum under ter- restrial applications. Hence, the highest theoretical efficiency limit of over 29% is possible for single- junction cells. The CdS/CdTe layers for the flexible solar cells with record specific power can be deposited on Poly/ITO substrate by thermal vacuum evaporation method (fig 1). Fig. 1 Vacuum chamber for thermal vacuum evaporation of CdTe and CdS films. Polycrystalline CdTe thin film solar cells have shown long-term stable performance and high effi- ciency up to 16.5% under AM 1.5 illumination. BInnovative Aspect and Main Advantages • Low cost if produced in large volumes (over • 60MW/year - 1Euro/Wp). Simple deposition technology makes it very prom- ising for industrial application. • Considerable weight reduction due to use of only a few micrometers thick film layers on lightweight flexible substrate compared to glass substrate which represents over 98% of the total weight of solar cells. • The CdTe SCs have the highest stability under proton and electron irradiation compared to other photovoltaic devices, which makes CdTe cells very prospective for space application. Fig. 2 CdTe solar cells on glass substrate (in grams) Fig. 3 Flexible CdTe solar cells (in grams) Table 1. Comparison of conventional SCs on glass sub- strate and flexible SCs on polyimide Glass 793 Polyimide 765 SC parameters Open circuit voltage Voc, mV Shot current density Jsc, mA/cm2 Fill factor FF Efficiency η, % Specific kW/kg power, 19,9 0,71 11,2 0.025 20,9 0,71 11,4 2.5 BAreas of Application Flexible cells give much more possibilities for space ap- plication, integration in buildings, and can be applied in small cards, consumer electronics, solar cars and boats. Stage of Development One Ukrainian patent, and further international patent pending. Further development, licensing, and technology transfer is sought. BContact Details Contact persons: Associate Prof. Khrypunov Gennadiy S. National Technical University “ Kharkov State Polytechnic Institute” Frunze St., 21 , Kharkov , 61002, Ukraine Tel: +380 542 971928 ; e-mail: khrip@ ukr.net Prof. Nickolai Klyui Address: 41, Prospect Nauki., Kyiv, Ukraine, 03028. Uklyui@isp.kiev.uaU Ph./fax (38044)-525-62-02.; E-mail: H H 0 1 2