Cu(In,Ga)Se2 and CdTe heterojunction solar cells grown on rigid (glass) or flexible foil substrates require p‐type absorber layers of optimum optoelectronic properties and n‐type wide‐bandgap partner layers to form the p–n junction. Transparent conducting oxide and specific metal layers are used for front and back electrical contacts. Efficiencies of solar cells depend on various deposition methods as they control the optoelectronic properties of the layers and interfaces. Certain treatments, such as addition of Na in Cu(In,Ga)Se2 and CdCl2 treatment of CdTe have a direct influence on the electronic properties of the absorber layers and efficiency of solar cells. Processes for the development of superstrate and substrate solar cells are reviewed. Copyright © 2004 John Wiley & Sons, Ltd.

This paper reports the external quantum efficiency (EQE) of encapsulated screen-printed crystalline silicon solar cells, where the encapsulation includes a layer of luminescent down-shifting (LDS) molecules. At wavelengths less than 400 nm, the inclusion of the LDS molecules increases the EQE from near zero to, at most, 40%. The increase in EQE corresponds to a rise in short-circuit current density of 0Á37 W 0Á13 mA/cm 2 under the AM1-5g spectrum.

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Processing of CdTe/CdS solar cells requires annealing of CdS and CdTe/CdS in different ambients. It has been proven that the application of a CdCl 2 treatment (or its variant) is important for high ef®ciency solar cells. This treatment in¯uences the structural and interface properties of the layers. We have grown CdS layers either by a chemical bath deposition (CBD) or a high vacuum evaporation (HVE) on different transparent conducting oxides (TCO): tin oxide doped with¯uorine (FTO) and indium tin oxide (ITO) coated glass substrates. The CdTe layers have been grown by a HVE method. Effects of the CdCl 2 treatment on the recrystallization of CdTe and CdS have been studied with X-ray diffraction and scanning electron microscopy. An increase in the grain size of CdTe from about 0.5 to 3±7 mm, along with the loss of the preferred (111) growth orientation has been observed. The strain and recrystallization of CdTe, and intermixing of the CdTe and CdS layers strongly depend on the deposition and annealing temperatures. An optimum treatment and a minimum thickness of CBD±CdS is required for high ef®ciency solar cells. CdS layers and the method of their deposition also have a strong in¯uence on the microstructure of CdTe and photovoltaic properties. Solar cells with ef®ciency of 11.2 and 2.5% are obtained with HVE and CBD grown CdS window layers. q