Ivan Clemminck

SCREEN PRINTED AND SINTERED CdTe-CdS SOLAR CELLS

Screen printed and sintered CdTe-CdS solar cells differ in some aspects from other CdTe cells: the layers are thicker, the fabrication temperatures higher, the grain size is usually better. A good morphology, a good junction behaviour and consequently a high open circuit voltage, and efficient doping of the CdTe are seen to be an inherent advantage of the screen printing and sintering technology. On the other hand, care has to be taken to avoid strong interdiffusion and optical transmission loss in the CdS window.

Screen Printing of CIS Films for CIS-CdS Solar Cells

The possibility of screen printing the CuInSe2 layer in CuInSe2-CdS solar cells is studied. Requirements on resistance and layer interaction impose the structure: Mo-screen pinted CuInSe2-evaporated CdS. Crystallographic, optical and electrical properties of the screen printed and sintered CIS films are given. The complete structure has a high J sc , exceeding 30 mA/cm2, but FF and FF and V oc are low. Reasons for the low FF are analysed. An alternative way to obtain CIS by screen printing Cu and In, followed by selenisation, is discussed.

Electrical and microstructural properties of screenprinted CdS layers for CdS-CdTe solar cells

Results are presented on an investigation into the development of electrical and microstructural properties of sintered CdS films as a function of sintering parameters, and the double role of the evaporating flux is illustrated. CdCl/sub 2/ used in the sintering, acting both as a sintering flux and as an n-type dopant. The sintering temperature and sintering period were varied, and special attention was paid to the controlling of the flux evaporation. A study of the microstructural and electrical properties was performed, using SEM-analysis, atomic absorption spectroscopy, resistivity, and Hall measurements. Data are presented on grain size, sheet resistance, carrier concentration, and carrier mobility versus sintering parameters. The results are explained in terms of the double role of the evaporating flux. It is found that the microstructure of screen-printed CdS films, sintered with the aid of CdCl/sub 2/ as a flux, is determined by the sintering temperature and by the effective sintering period, which is the period during which the flux can be kept active within the film.<<ETX>>

Growth studies of CuInSe/sub 2/ using Cu-Se fluxes

The latest developments in CIGS/CdS/ZnO solar cells show the importance of understanding the growth mechanisms of the absorber layer. For this purpose, the authors studied the influence of Cu, CuSe, Cu/sub 2/Se and Se as additives to a CuInSe/sub 2/ base material. They found that, in a selenium rich atmosphere, the copper rich phase forms CuSe, which acts as a flux in a liquid phase sintering (above its melting temperature of 523/spl deg/C). Testing their findings to the selenization of glass/Mo/In(Se)/Cu structures led to marked grain growth with grains up to 20 /spl mu/m.

Screen printing of CdS pastes for CdS-based solar cells

The screen-printing properties of slurries made with three organic binders are discussed. They are ethyl cellulose (EC), glycerol, and propanediol (PD). A procedure is described to meet the requirements for the removal of ethyl cellulose (oxygen required) and the sintering of the CdS film (oxygen absolutely to be avoided). It is observed that no good quality CdS screen prints are obtainable with a PD-slurry. It is also clear from the results that the choice of an optimal set of screen printer settings can give only minor improvements. The composition of the slurry, and more specifically the choice of the organic binder, has far more influence. It is shown that the choice of an ethyl cellulose binder makes it possible to screen print much smoother films, with a sharper edge definition. It is shown that the CdS layer, screen printed from EC-slurries, has the same electrical and morphological properties as the films printed from a PD-slurry.<<ETX>>

Solid-state coulometric titration study of sputtered CuxS layers

In this paper solid-state coulometry (SSC) is used as a technique to identify the composition of sputtered Cu x S layers. The effects of heat-treatments and electrochemical reduction on the film composition were also studied. Different methods to measure the stoichiometry index x were compared

On the interpretation of solid-state coulometry, used in studies of thin films of copper sulphide

Etude de la reduction electrochimique des couches minces de CuO et de Cu 2 S sur une electrode de cuivre