CdS is electrodeposited on CIGS without post treatment and achieved photoresponse

1. Figure a & b shows the visual appearance and surface morphology of as-grown
electrodeposited CdS on Molybdenum substrate
 Figure c shows the CdS thin film on FTO substrate with a transmittance of about
74.5% and band gap of 2.41 eV for 70nm thickness
Figure d shows the XRD analysis which confirms the presence of CdS with hexagonal
crystal orientation with CIGS layer deposited on Molybdenum substrate
Application of Electrodeposited CdS as n-type Semiconductor Layer
for CIGS based Thin Film Solar Cells
B.Divya1,2, Ramachandraiah A2 and Bulusu V. Sarada1*
1Centre for Solar Energy Materials, International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI),Balapur,
Hyderabad – 500005, Telangana, India.
2Department of Chemistry, National Institute of Technology, Warangal - 506004, Telangana, India.
*Corresponding author: sarada@arci.res.in
INTRODUCTION:
CIGS based thin film
photovoltaics use Cadmium sulfide
(CdS) as an effective n-type
semiconductor layer which satisfies
the basic requirement of forming pn
–junction as shown in Figure1.
CdS layer must be as thin as
possible (50-70 nm) to allow the
sunlight reach the absorber layer.
Commercially, Chemical Bath
Deposition (CBD) is the most widely
used technique due to its simplicity,
cost effectiveness where as the
quality of film depends on the
temperature of the bath,
concentrations of the solutions and
pH [1]
ACKNOWLEDGEMENTS: Authors would like to thank and
acknowledge the contributions made by Dr.M.Sreekanth, Dr. Prashant
Misra, Jyothi Gupta for their support in characterization
REFERENCES:
1. V. Kumar, I. Packiaselvam, K. Sivanandan, M. a Vahab, and a K. Sinha, Chemical Solution Deposition of (Ba, p. 1136-1139, (2006).
2. J. Tao and S. Yu, Sol. Energy Mater. Sol. Cells, 141, 108–124 (2015) http://dx.doi.org/10.1016/j.solmat.2015.05.005.
ABSTRACT:
Electrodeposition (ED) process as a non vacuum technique is emerging to manufacture
thin film solar cells such as CIGS, CZTS , CdTe etc., to reduce the cost as the
commercially available thin film solar cells are made from vacuum methods such
Physical Vapor Deposition (PVD). In the present study, Cadmium Sulfide (CdS) thin
films developed by electrodeposition at room temperature have hexagonal crystal
structure with no post-treatment and showed high photoactivity compared to chemical
bath deposited CdS thin films.
CBD process produces colloidal CdS
precipitates as waste that are toxic when
disposed and need to recycle[2].
In this context, to limit the waste produced
during CBD process, electrodeposition (ED)
technique is explored which is advantageous
where the electrolyte can be reused for few
months by replenishing the ions consumed
and restricts the production of toxic waste
production .
EXPERIMENTAL:
Step 1: CIG is vacuum sputtered onto Mo substrate and then selenized in the presence of
Se vapor to form CIGS
Step 2: CdS is deposited using cathodic electrodeposition technique with 2 electrode
system at room temperature 25 °± 2 °C
Characterization: Photoactivity measurement using photoelectrochemical analyzer
equipped with Solar Simulator
SURFACE MORPHOLOGY & OPTICAL PROPERTIES
J-V CHARACTERISTICS OF
CIGS/Mo LAYER
Bare CIGS showed cathodic
photocurrent of about 0.052 mA cm-2
indicating p-type semiconductor
J-V CHARACTERISTICS OF
CdS/CIGS/Mo LAYER
Electrodeposition of CdS on CIGS
enhanced photocurrent which indicates
the increase of photons absorption and
effective electron-hole pair separation
I-t CHARACTERISTICS OF
CdS/CIGS/MO CONCLUSIONS
 Electrodeposited CdS thin films at
room temperature showed uniform
surface coverage
PEC measurements confirmed the
photoactivity of the Electrodeposited
CdS on CIGS and compared with
chemical bath deposited (CBD) CdS on
CIGS where high photocurrent is
observed for Electrodeposited CdS
compared to Chemical bath deposition.
 Hence, it can be concluded that
electrodeposition done at room
temperature can be used to deposit CdS
for the CIGS based thin film solar cells
with no further heat treatment
International Conference on Advanced Semiconductor Materials and Devices (ICASMD) 2018
Photoactivity of both ED and CBD CdS
deposited on CIGS and at -0.4 V.