POLYCRYSTALLINE SILICON SOLAR CELL PASSIVATION AT ROOM TEMPERATURE
Onkar S Shinde1,2, Subhash V Ghaisas2 and Neelkanth G Dhere1
1Florida
Solar Energy Center, University of Central Florida,1679 Clearlake Road, Cocoa, FL 32922-5703, USA
2School of Energy Studies, SP Pune University, Pune-411007, India.
RESULTS
INTRODUCTION
•  SEM And EDAX Analysis
We report, a simplified method for passivation of emitter surface of
a)
polycrystalline silicon solar cells at room temperature. The Olelyamine is used as
passivation agent. Passivation coating is applied successfully via spin coating
method at room temperature. Due to this coating it is seen that the efficiency of
solar cell is increased.
b)
a)
However, the process is not stable in terms of efficiency, at primary stage
after applying immediate coating the efficiency increased by 7% and after 40 hrs.
it becomes 16%.The slow efficiency reduction was observed over time due to
interaction of Olelyamine and CO2 .Humidity is also manifests this degradation.
PASSIVATION MECHANISM
d)
c)
Figure-2: SEM and EDAX of emitter surface of bare silicon solar cell in figure a and b without ARC.
SEM and EDAX of Olelyamine coated emitter surface of silicon solar cell in figure c and d
•  FTIR Analysis and QSSP minority carrier lifetime
Olelyamine(C18H35NH2)
Recombination lifetime(µs)
Sample
H
H
N
Passivated Bonds
Dangling Bonds
H
H
H
CH3+ or NH2+ or H+
H
Si
P
Si
Si
Si
Si
P
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
Si
HFTreated
Olelyamine
Coated
nEmitter of
solar cell
12.49
13.55
14.15
n-type
Silicon
Wafer
4.54
5.26
4.6
H
H
CH3+ or NH2+ or H+
HFUntreated
n-type
emitter of
a solar
cell
Si
Si
Figure-3:FTIR of emitter surface of Pure Olelyamine(red),
coated silicon solar cell(black and blue) and n type wafer
Olelyamine coated (green)..
Table1-Minority lifetime measurement of with and without
Olelyamine coating
•  Current –Voltage characteristics
Figure-1: Passivation Mechanism
Sample
In above figure 1 ,method of Olelyamine (C18H35NH2) coating on the solar cell n
type emitter surface is demonstrated. It is shown that the phosphorous is also
Isc
(mA)
Voc
(V)
ɳ (%)
%
Increment
in
Efficiency
Bare Solar 18.34 0.541 13.34
cell
playing the role in passivation (refer FTIR Analysis) and the surface of Silicon is
-
totally distinct characteristics than n-type wafer. This is due to shallow junction
Solar cell
With
Olelyamine
Coated
present in the si solar cell devices. The passivation layer and its contribution to the
increment in power conversion efficiency is discussed in this article.
It is a conventional p-n junction solar cell with p-type base and highly doped
n emitter with passivation coating SiNx is on top. This passivation layer and native
oxide removed from emitter surface with standard cleaning process.
Further ,sample subjected to EDAX for chemical analysis which demonstrates no
molecules from SiNx remained on surface of the solar cell which shown in figure 2a
and 2b. Then on the same sample Oleyamine is deposited at room temperature
and related SEM and EDAX is shown in Figure 2c and 2d.
20.5
0.549 15.20
13.94
Figure-4:I-V characteristics of Bare Silicon Solar cell and
Table 2- Summary of Current –voltage parameters of Silicon
Olelyamine coated silicon solar cell.
Solar cell
Acknowledgement
Authors are thankful to MNRE, Government of India and Solar Energy Research Institute for India and the United States. (SERIIUS)
funded jointly by the U.S. Department of Energy subcontract DE AC36-08G028308 (Office of Science, Office of Basic Energy
Sciences, and Energy Efficiency and Renewable Energy, Solar Energy Technology Program, with support from the Office of
International Affairs) and the Government of India subcontract IUSSTF/JCERDC-SERIIUS/2012 dated 22nd Nov. 2012.