Abstract
Microscopic structure and solar cell performance in hydrogenated mixed-phase thin film silicon (Si:H) solar cells are studied. The samples were made with RF glow discharge with different hydrogen dilution profiles. The material properties were measured with Raman, X-TEM, AFM, and C-AFM. Several interesting phenomena are observed. First, the cone-structured nanocrystalline aggregations were formed when a constant hydrogen dilution was used. Second, no uniform block-like (or cylinder-like) structured nanocrystalline clusters were observed even when hydrogen dilution profiling was optimized for this purpose. Instead, tree-like structured nanocrystalline clusters were formed and embedded in the intrinsic layer. Third, the magnitude of light-induced Voc increase was reduced by hydrogen dilution profiling. When the dilution profiling was sufficiently steep, no light-induced Voc increase was observed. Instead, the Voc decreased after light-soaking regardless of the crystalline volume fraction. In addition, AFM and C-AFM showed that this type of mixed-phase material has hill-like surface structure, where the hills correspond to nanocrystalline clusters. The local current density in hill-like areas was much higher in the samples made with constant hydrogen dilution than those using hydrogen dilution profiling. For the samples with a very steep hydrogen dilution profiling, the local forward current density is very low. Based on our previous model, the light-induced Voc increase depends on the formation of the current path in the nanocrystalline cluster areas. When a steep hydrogen dilution profiling is used, the tree-like nanocrystalline clusters are isolated and embedded in the intrinsic layer, therefore, no high current paths are formed and no light-induced Voc increase is observed.
Original language | American English |
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Pages (from-to) | 513-516 |
Number of pages | 4 |
Journal | Physica Status Solidi (C) Current Topics in Solid State Physics |
Volume | 7 |
Issue number | 3-4 |
DOIs | |
State | Published - 2010 |
Event | 23rd International Conference on Amorphous and Nanocrystalline Semiconductors, ICANS23 - Utrecht, Netherlands Duration: 23 Aug 2009 → 28 Aug 2009 |
NREL Publication Number
- NREL/JA-520-48845
Keywords
- thin film solar cells