Incoherent Propagation of Light in Coherent Models

Transcription

1 Incoherent Propagation of Light in Coherent Models Andrej Čampa, Janez Krč and Marko Topič University of Ljubljana Faculty of Electrical Engineering Tržaška cesta 25, SI-1000 Ljubljana, Slovenia

2 Outline Introduction Incoherent propagation of light Thinning down the incoherent layer Model Results Conclusions 2

3 Example of a-si thin-film solar cell structure air 1. Incoherent propagation of light 2. Thining down of thick glass layer - mm range to nm range! 3

4 Incoherent propagation of light In many optical cases light loses coherence: 1. Spatial incoherence 2. Spectral incoherence 3. Temporal incoherence Incoherent light does not interfere, we have to eliminate constructive and destructive interference in coherent models Constructive interference E Destructive interference + = + = 4

5 Incoherent propagation of light In rigorous simulations interference term of Poynting vector has to be eliminated Interference term Correcting the thickness by very small value 5

6 Incoherent propagation of light Two approaches: a) Phase matching method - the structure needs to be well defined to find the phase shift of the reflected wave interference term = 0 π + mπ φ d = Re[ 2 ], m = 0, ±1, ±2, 2k a) Phase elimination approach - the phase is eliminated by two simulation runs - more appropriate for structure that are not well defined interference term (d) interference term (d ) = 0 d λ = d Re[ 4N(λ) ] *A. Campa et al., "Two approaches for incoherent propagation of light in rigorous numerical simulations," Progress In Electromagnetics Research, Vol. 137, ,

7 Thinning down the incoherent layer Interference term glass glass Solar cell d~500 nm + Dd(l) Solar cell *A. Campa et al., "Two approaches for incoherent propagation of light in rigorous numerical simulations," Progress In Electromagnetics Research, Vol. 137, ,

8 Deposition direction Model Non-conformal growth model ITO mc-si:h ZnO/Ag g mc-si:h =0.3 g Ag, ZnO =0.2 excitation PML *M. Sever et. al., Combined model of non-conformal layer growth for accurate optical simulation of thin-film silicon solar cells, Sol. energy mater. sol. cells., Vol. 119, (2013) 8

9 Model ITO Wavelength dependent mesh Realistic optical constants (layers) 9

10 Results thick glass layer Incident plane wave R T T Incoherent glass layer 1 mm thick R&T 0.2 phase matching, d ~ 1 m phase elimination, d ~ 1 m coherent calculation, d = 1 mm measured R R T wavelength [nm] wavelength [nm] 10

11 Results thin-film amorphous silicon solar cell 11

12 Results Air Thick glass Jülich TCO (0.8 mm) a-si:h cell (i- 350 nm) Cell made and measured at Inst. of Energy Research (IEK-5) Photovoltaics, FZJ Ag mc-si:h cell (i- 1.0 mm) Back TCO (80 nm) 12

13 Results simulations measurements Air Thick glass B52 (2.5 mm) a-si:h cell (i- 250 nm) mc-si:h cell (i- 1.2 mm) B52 (2.5 mm) Cell made and measured at École Polytechnique Fédérale de Lausanne - EPFL White paint 13

14 Conclusions Optical simulations including thick incoherent layer were shown a) using phase matching method b) using phase elimination method c) thinning down thick layer Results of simulations compared with realized cells of different institutes 14

15 Acknowledgments FP7 Fast Track project (GA No.: ) Accelerated development and prototyping of nano-technologybased high-efficiency thin-film silicon solar modules Slovenian Research Agency - ARRS A. Čampa et al. COMSOL 2013, October 24th, Rotterdam, Netherlands 15

16 Thank you for your attention 16

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18 incoherent glass incidence from glass 0.6 A e-7 6.0e-7 8.0e-7 1.0e-6 1.2e-6 wavelength [nm] 18