On the physics of microcrystalline silicon thin film solar cells: from the material to devices with high conversion efficiencies
On the physics of microcrystalline silicon thin film solar cells: from the material to devices with high conversion efficiencies
VHF-PECVD was uséd to prepare doped and undoped microcrystalline silicon forapplications in thin-film solar tells. In addition, device preparation processes on glass substrates,covered with texture-etched zinc-oxide films, were developed. High conversion efficiencies of up to8.7 % and 10 % for singl...
| Personal Name(s): | Vetterl, Oliver (Corresponding author) |
|---|---|
| Contributing Institute: |
Publikationen vor 2000; PRE-2000; Retrocat |
| Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
2001
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| Physical Description: |
X, 126 p. |
| Document Type: |
Report Book |
| Research Program: |
ohne Topic |
| Series Title: |
Berichte des Forschungszentrums Jülich
3897 |
| Link: |
OpenAccess OpenAccess |
| Publikationsportal JuSER |
|
VHF-PECVD was uséd to prepare doped and undoped microcrystalline silicon forapplications in thin-film solar tells. In addition, device preparation processes on glass substrates,covered with texture-etched zinc-oxide films, were developed. High conversion efficiencies of up to8.7 % and 10 % for single junction solar tells and stacked solar tells were achieved, respectively. Thedeposition conditions of the intrinsic absorber layer were varied over a vide range and materialproperties such as crystalline volume content, conductivity and optical absorption as well ascorresponding solar tell properties were investigated. It was found that the structural compositionof the material is closely related to transport and recombination properties, resulting in optimumdevice performance under unexpected conditions close to the transition to amorphous growth.In particular, the dark conductivity of the material decreases upon approaching this transitionstarting from the highly crystalline range, e.g. by changing the dilution ratio of silane in hydrogen,while the efficiency of corresponding solar tells improves due to increasing open-circuit voltages.Simultaneously, the drawback of recombination losses observed for highly crystalline conditions,which tan be attributed to a high defect density, is much improved. The upper limit of theefficiency improvement is reached at the set-in of amorphous growth. This transition occurs veryabruptly in the solar tells due to local epitaxy on the doped contact layers. Beyond this point thebeneficial increase of open-circuit voltage is overcompensated by a significant reduction of chargecarrier generation and extraction efficiency. It is concluded that growth conditions close to thetransition to amorphous growth, which in the solar tell still result in structurally homogeneousand highly crystalline material, are most suitable with respect to the device performance. |