Light induced changes in the electrical behavior of CdTe and Cu(In,Ga)Se2 solar cells

Modelling the quantum efficiency of cadmium telluride solar cells

“…Acceptor concentrations as high as 10 15 cm À 3 are reported [19,20]. Other authors assume that the doping is in the same order of magnitude but is compensated to an effective doping of about 10 14 cm À 3 [21,22]. Kosyachenko et al [23] assume a high concentration of native impurities and defects (more than 10 15 cm À 3 ), which should be exceeded significantly by the concentration of shallow acceptor impurities in order to minimize the electrical losses.…”

“…(8)-(10), (17), (20) and (21) and the consideration of optical losses in the substrate by transmitted intensity T substrate yields the total external quantum efficiency…”

“…For low lifetimes, a high IQE is obtained when W is 1 mm since the electrical field is higher (see Eq. (21)) and the collection is more effective. In this case however, the contribution of the neutral region is negligible since t e is too small for the carriers to reach the space-charge region.…”

Development of thin‐film Cu(In,Ga)Se2 and CdTe solar cells

“…Therefore, it has become common routine 123,124 that CdTe/CdS stacks are subjected to heat treatments under Cl-containing ambient at temperatures between 350 and 600 C. Furthermore, the presence of oxygen during annealing is beneficial. 125 This annealing procedure in Cl-O ambient is called 'CdCl 2 treatment' or 'junction activation.' Both for low-and high-temperature grown cells the effect is an improvement of the structural quality of the layers and of the electronic characteristics.…”

“…While Cu-based back contacts form barriers smaller than 0Á25 eV with the CdTe layer, barrier heights reported 125,164 for proven long-term stable devices are in the range of 0Á35-0Á5 eV. Despite the higher initial efficiency the detrimental effect of Cu-based back contacts on the long-term stability suggest that Cu should be avoided for commercial modules.…”