Fourmond, E.

Giglia, V

Varache, R.

Veirman, J.

HAL-CEA

Influence of Surface Defectivity on the Performances of Silicon Heterojunction Solar Cells

HAL Université de Savoie

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HAL Id: hal-02321708
https://hal.archives-ouvertes.fr/hal-02321708
Submitted on 21 Oct 2019
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Influence of Surface Defectivity on the Performances of
Silicon Heterojunction Solar Cells
V Giglia, J. Veirman, R. Varache, E. Fourmond
To cite this version:
V Giglia, J. Veirman, R. Varache, E. Fourmond. Influence of Surface Defectivity on the Performances
of Silicon Heterojunction Solar Cells. European Photovoltaic Solar Energy Conference, Sep 2019,
Marseille, France. ￿hal-02321708￿
Commissariat à l’énergie atomique et aux énergies alternatives
17 rue des martyrs | 38054 Grenoble Cedex
www-liten.cea.fr
UNDERSTANDING OF THE INFLUENCE OF THE SURFACE DEFECTIVITY ON SILICON 
HETEROJUNCTION CELL PERFORMANCE.
V.Gigliaa,b, J.Veirmana, R. Varachea, E.Fourmondb
Corresponding author: valentin.giglia@cea.fr
a) CEA, LITEN, Department of Solar Technologies, F-73375 Le Bourget du Lac, France
b) Univ. Lyon, INSA-Lyon, INL UMR5270, F-69621 Villeurbanne, France
Commercially available bulk lifetimes ↑
Production tools throughputs ↑
Defectivity importance likely to increase
Conclusions:  Predict the influence of cell parameters on the 
performance losses (r, bulk lifetime).
 Study the influence of defectivity properties
(spatial distribution, location (BS/FS), size …).
 Suggest ways to mitigate losses.
Combined experimental-modellisation approach.
Strong impact of surface defectivity mostly on FF 
according to [1].
The depassivated region high recombination rate 
induces a force increasing with the voltage towards
itself leading to important FF losses.
Perspectives:
Necessary to quantify and 
understand the defectivity-
induced efficiency (h) losses
Creation of a 
controlled 
defectivity protocol
Exp. Quantification 
of defectivity 
induced losses
Validation of the 
modelled structure
Identification of 
physical 
mechanisms
Experimental approach Simulation approach
Normalised Isc
I(V) measurements 
Simulation results 
0,925
0,950
0,975
1,000
Normalised FF
0 3 6 9
0,925
0,950
0,975
1,000
Normalised Efficiency
number of scratches
0 3 6 9
Normalised Voc
number of scratches
 A scratch every 9 pitches (total c-Si 
surface depassivation).
 Choice of Busbarless metal scheme 
easy scratch creation and facilitated 
simulation.
Protocol for the creation of a well-
defined defectivity
 Controlled defectivity on 
busbarless cells:
 FF losses = 2/3 of efficiency losses.
 Good scratch-to-scratch repeatability.
 0.2% surface scratched = -6%rel h !
 Good agreement experiments/simulation
 Quantification of defectivity- induced 
efficiency (h) losses
 Validation of the modelled  
2D structure (ATLAS Silvaco)
 Physical mechanisms:  
 Same defectivity distribution as 
the actual cells.
 Parametrization based on SHJ 
cells characterization.
 Defect: locally maximized Dit.
0 20 40 60 80 100 120 140 160
-0,7
-0,6
-0,5
-0,4
-0,1
0,0
Depassivated region effect
Emitter effect
BSFSBS
b) with a depassivated region
Increasing voltage
 Jsc
 0,3V
 0,45V
 0,49V
 0,53V
 0,57V
 0,61V
 mpp
 0,65V
 0,69V
 0,73V
 Voc
Depth (µm)
 F
,h
 (e
V
)
Increasing voltage
a) without a depassivated region
FS
Emitter effect
20 40 60 80 100 120 140 160
Depth (µm)
0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8
0
10
20
30
40
 Without defectivity
 With defectivity
Voltage (V)
C
ur
en
t d
en
si
ty
 (m
A
/c
m
²)
Vt
c) I(V) comparision with
or without a depassivated
 region
0
5
10
15
90
100
 Relative J losses  
R
elative J losses (%
)
 Minority charge carrier quasi fermi level 𝜀ி,௛.
 Force applied on holes ≈ 𝛻𝜀ி,௛
Force towards the defect increasing with the voltage
 On 10 cells : I(V) measurements after 
each scratch.
𝛻𝜀ி,௛ profile in the c-Si at the short circuit working point (Jsc):
Vertical profile of 𝜀ி,௛ from the c-Si front side FS to its back side BS.
The study of 𝜀ி,௛ explains the mechanisms
behind the h losses.
I(V) curves with and without a 
depassivated region
 Carriers photogenerated within the affected region
(pink) recombine in the depassivated region.
 1,4% of carriers are lost  Jsc losses = 1,4%rel.
 The same analysis also holds for the other I(V) 
parameters losses (presented in the article). 
Context of the study
Approaches used to carry out the study
Presentation of the study
c-Si
 Allows to trust the code to investigate the mechanisms behind h losses
Towards the 
back surface
Electron contact layer
Hole contact layer
[5] O.Nos, “Quality control method based on photoluminescence imaging for the performance predictionof c-Si/a-Si:Hheterojunction solar cells in industrial production lines”,2016, Solar Energy Materials and Solar Cells


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Hal - Université Grenoble Alpes

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Influence of Surface Defectivity on the Performances of Silicon Heterojunction Solar Cells

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