| 1. |
- Edoff, Marika, 1965-, et al.
(författare)
-
High Voc in (Cu,Ag)(In,Ga)Se2 Solar Cells
- 2017
-
Ingår i: IEEE Journal of Photovoltaics. - 2156-3381 .- 2156-3403. ; 7:6, s. 1789-1794
-
Tidskriftsartikel (refereegranskat)abstract
- In this contribution, we show that silver substitution for copper in Cu(In,Ga)Se-2 (CIGS) to form (Ag,Cu)(In, Ga)Se-2 (ACIGS) leads to a reduction of the voltage loss expressed as E-g/q-V-oc. This, in turn, leads to higher device efficiencies as compared to similar CIGS devices without Ag. We report V-oc at 814 mV at a conversion efficiency of 21% for our best ACIGS device with 20% of the group I element consisting of silver. Comparing ACIGS and CIGS devices with the same Ga/(Ga+ In) ratio, the ACIGS devices exhibit about 0.05 eV higher bandgap. Alkali postdeposition treatment with KF leads to improvements in efficiency both for CIGS and ACIGS, but we find that the dose of KF needed for optimum device for ACIGS is 10-20% of the dose used for CIGS.
|
|
| 2. |
- Larsen, Jes K, et al.
(författare)
-
Sulfurization of Co-Evaporated Cu(In,Ga)Se-2 as a Postdeposition Treatment
- 2018
-
Ingår i: IEEE Journal of Photovoltaics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2156-3381 .- 2156-3403. ; 8:2, s. 604-610
-
Tidskriftsartikel (refereegranskat)abstract
- It is investigated if the performance of Cu(In,Ga)Se-2 (CIGSe) solar cells produced by co-evaporation can be improved by surface sulfurization in a postdeposition treatment. The expected benefit would be the formation of a sulfur/selenium gradient resulting in reduced interface recombination and increased open-circuit voltage. In the conditions used here it was, however, found that the reaction of the CIGSe layer in a sulfur environment results in the formation of a CuInS2 (CIS) surface phase containing no or very little selenium and gallium. At the same time, a significant pile up of gallium was observed at the CIGSe/CIS boundary. This surface structure was formed for a wide range of annealing conditions investigated in this paper. Increasing the temperature or extending the time of the dwell stage had a similar effect on the material. The gallium enrichment and CIS surface layer widens the surface bandgap and therefore increases the open-circuit voltage. At the same time, the fill factor is reduced, since the interface layer acts as an electron barrier. Due to the balance of these effects, the conversion efficiency could not be improved.
|
|
