Programm Photovoltaik Ausgabe 2008 ... - Bundesamt für Energie BFE
Programm Photovoltaik Ausgabe 2008 ... - Bundesamt für Energie BFE Programm Photovoltaik Ausgabe 2008 ... - Bundesamt für Energie BFE
3/6 The specific scientific and technological project objectives are: � To demonstrate the fabrication of ultra-high-efficiency silicon heterojunction solar cells (>20% on “standard” configurations or even higher with novel device structures), based on a combination of amorphous/microcrystalline layers and thin crystalline wafers (down to 100µm). � To demonstrate that the process is up-scalable to large area solar cells (>100cm 2 ) which should achieve efficiency over 20%. � To demonstrate a new metallization/encapsulation process capable to lead to a fabrication of high-efficiency and lightweight (
Seite 44 von 288 Results The amorphous/crystalline silicon heterojunction solar cells with the highest open-circuit voltage of 705 mV [1] and the highest efficiency of 19% [2] still date from before the project start. Their IV-curves are shown in Fig. 3. Fig. 3: Current-voltage curves of our up to now best flat silicon heterojunction solar cells. However, the current of these flat heterojunction solar cells is limited by front surface reflection, because of the surface flatness, instead of random pyramids. Therefore, for the moment, we have limited our efforts on flat crystalline silicon wafers to interface recombination studies and have improved our cell results on textured crystalline silicon. At the beginning of our work with crystalline silicon, after having grown several amorphous silicon layers on different wafers, we started wondering about the differences in measured lifetime curve shapes. Literature research for the modeling of injection level dependent lifetime curves led us to a formalism that considers Shockley-Read-Hall recombination at the crystalline silicon interface, such as considered for silicon dioxide and silicon nitride. But in fact, we discovered that the amorphous/crystalline silicon interface defects are dangling bonds that can have three different charge states (instead of two as for SRH). Considering this amphoteric nature of the present interface defects for lifetime curve modeling purpose, we fall back on a closed-form dangling bond recombination rate that was found in our laboratory 15 years ago. Fig. 4 shows the good accordance of experiment (symbols) and modeling (lines), in the case of intrinsic amorphous silicon passivating various crystalline silicon substrates. Fig. 4: Injection-level dependent lifetime curves of differently doped crystalline silicon substrates passivated by intrinsic amorphous silicon. Symbols show experiments and lines modeling with our amphoteric interface recombination model [3]. THIFIC, S. Olibet, IMT Neuchâtel 4/6
- Page 1: Forschung, April 2008 Programm Phot
- Page 4 and 5: Programm Photovoltaik Ausgabe 2008
- Page 6 and 7: T. Meyer ORGAPVNET: Coordination Ac
- Page 8 and 9: PROGRAMM PHOTOVOLTAIK Eidgenössisc
- Page 10 and 11: 1. Programmschwerpunkte und anvisie
- Page 12 and 13: Ein neues KTI-Projekt Flexible Phot
- Page 14 and 15: In einem neuen, durch den Axpo Natu
- Page 16 and 17: Performanz und Energieproduktion vo
- Page 18 and 19: ERGÄNZENDE PROJEKTE UND STUDIEN En
- Page 20 and 21: in diesem Projekt für die Koordina
- Page 22 and 23: 5. Pilot- und Demonstrationsprojekt
- Page 24 and 25: Produktionskapazität von insgesamt
- Page 26 and 27: [26] H. Häberlin, L. Borgna, D. Gf
- Page 28 and 29: [89] Konzept der Energieforschung d
- Page 30 and 31: Solarzellen C. Ballif, J. Bailat, F
- Page 32 and 33: Département fédéral de l’envir
- Page 34 and 35: 3/9 Fig. 1: Refractive index n and
- Page 36 and 37: 5/9 V oc [mV] 940 920 900 880 860 8
- Page 38 and 39: 7/9 Fig. 5: Top) SEM micrographs of
- Page 40: 9/9 Acknowledgements The co-workers
- Page 43 and 44: Seite 40 von 288 Introduction and f
- Page 45: Seite 42 von 288 Introduction / Pro
- Page 49 and 50: Seite 46 von 288 Collaborations IMT
- Page 51 and 52: Seite 48 von 288 Introduction / Pro
- Page 53 and 54: Seite 50 von 288 High efficiency so
- Page 55 and 56: Seite 52 von 288 Towards low costs
- Page 58 and 59: Eidgenössisches Departement für U
- Page 60 and 61: 3/6 The Athlet consortium comprises
- Page 62 and 63: 5/6 Large area cluster deposition s
- Page 64 and 65: SIWIS Département fédéral de l
- Page 66 and 67: 3/6 Results Defects characterizatio
- Page 68 and 69: 5/6 The test methodology was optimi
- Page 70: Département fédéral de l’envir
- Page 73 and 74: Seite 70 von 288 Summary of Applied
- Page 75 and 76: Seite 72 von 288 Table 5 summarizes
- Page 78 and 79: Eidgenössisches Departement für U
- Page 80 and 81: 3/7 Figure 1: Vacuum deposition equ
- Page 82 and 83: 5/7 Testing of thickness, chemical
- Page 84: 7/7 Figure 6: Large area flexible s
- Page 87 and 88: Seite 84 von 288 Introduction / Pro
- Page 89 and 90: Seite 86 von 288 Intensity / arb. u
- Page 92 and 93: LARCIS Eidgenössisches Departement
- Page 94 and 95: 3/6 Work and results Alternative Ba
3/6<br />
The specific scientific and technological project objectives are:<br />
� To demonstrate the fabrication of ultra-high-efficiency silicon heterojunction solar cells (>20% on<br />
“standard” configurations or even higher with novel device structures), based on a combination<br />
of amorphous/microcrystalline layers and thin crystalline wafers (down to 100µm).<br />
� To demonstrate that the process is up-scalable to large area solar cells (>100cm 2 ) which should<br />
achieve efficiency over 20%.<br />
� To demonstrate a new metallization/encapsulation process capable to lead to a fabrication of<br />
high-efficiency and lightweight (
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