1. Crystalline Zinc Indium Selenide thin film
electrosynthesis
and
its photoelectrochemical studies
By
Anuradha Bhalerao-Pawar, B.G. Wagh, N.M. Shinde, S. B.
Jambure, C.D.Lokhande
K.K.Wagh Institute of Engineering Education & Research, Nasik
K.K.Wagh Arts, Commerce & Science College, Pimpalgaon Nasik.
Department of Physics, Shivaji University, Kolhapur.

2. Outline
1. a. Thin Film Science and
b. Thin Film Deposition Techniques
2. Electrodeposition of Zinc Indium Selenide
Thin films
3.
Structural Analysis of Thin Film
4.
PEC Study of Thin Film

3. 1a. Thin Film Science
Third Dimension
Negligibly
Smaller
Two
Dimensional
Solids
Thickness less
than 100nm
Thin
Film

4. Effect of Film Thickness on Material Properties
When Thickness is comparable with
Mean Free Path of Electrons
Resistivity & Dielectric constants
Vary as a function of thickness
Rigidity & Transparency
Alters with thickness

5. 1b. Thin Film Deposition Techniques
Physical Deposition :
One of the Physical
Properties is Altered
Chemical Deposition:
Use of Chemical
Reaction
Biological Deposition :
Use of Biological
Reaction
Hybrid Deposition:
Mixing of Above
Techniques
Electrochemical Deposition

6. Experimental Set-Up
• Experimental
set
up
consists of :
1. Anode
Counter Electrode (C)
2. Cathode
Working Electrode (W)
3. A Suitable Electrolyte.
• When electric current
passed through electrolyte:
Ionic movement starts

7. Experimental Mechanism
W
- +++
--- - +- ++ ---+
C
+
+
+
+
+
+
Charge Transfer across
Electrode and Electrolyte
causes
Charge Cloud formation near
the Electrodes
Positive ions deposit on cathode
forming a thin film.
The amount of material electroplated depends upon:
The direction of current existing at particular region of electrode.
The uniform current distribution :
A uniform film.

8. 2.
Electrodeposition
of
Zinc Indium Selenide Thin Films

9. Experimental Details
Working
Electrode
Stainless Steel Plate
with Surface
Treatments
Counter
Electrode
Reference
Electrode
Graphite Rod
Standard Calomel
Electrode (SCE)
Electrolyte: ZnSo4 (0.2M), InCl3 (0.02M) and SeO2 0.002M)
Temperature :
Ambient
pH : 2.2
Potential :
-600mV

10. Potential Optimization
Potential Vs SCE (mV)
0
200
400
600
800
1000
c
2
Current Density (mA/cm )
0
a
1
2
b
d
3
4
ZnSO4
InCl3
SeO2
ZnSO4+InCl3+SeO2
5
The polarization curves for reduction of (a) zinc, (b) indium,
(c) selenium and (d) for the bath containing precursor solutions

11. 3.Structural Analysis
Intensity (A.U.)
(Substrate )
(400)
800
(116)
(112)
1000
(301)
(220)
ZnIn2se4 Data
JCPDS File No. 39-1156
600
400
200
10
20
30
40
50
60
70
80
Degree)
The X-ray diffraction pattern of as-deposited ZnIn2Se4 thin film shows
Tetragonal crystal structure with remarkable growth along (220) plane

12. Surface Morphology
The scanning electron micrographs of ZnIn2Se4 film electrode
at magnification 10,000 over growth observed
And at 30,000 magnification : Well resolved uniform grain growth observed. Local
edge sharing rod like structure observed with breadth in nanorange (500nm )

13. Optical Absorbance Study
60000
% Absorbance
x 10-11(eV/cm)2
Absorbance
300
400
500
600
700
800
W avelength (  ) (nm )
 h  
30000
0
1.6
2.0
2.4
2.8
3.2
3.6
4.0
4.4
h(eV)
Inset shows : Material shows good absorbance in wavelength region 400-500nm
Energy band gap of the material : 2.4eV
Blue Shift of 0.1eV

14. 4.Photo Electrochemical [PEC] Study of Thin Film
PEC Cell
Solid – Electrolyte Junction
Electrochemical Photovoltaic
Cell (ECPV Cell)
Free Energy Change = 0
Photo Electrode
(Thin Film)
Photoelectrosynthetic Cell
Free Energy Change Non Zero
Electrolyte
Counter Electrode

15. Use of Zinc Indium Selenide Thin Film as Photo
Electrode in S-E Junction
Space Charge
+
+
+
+
Bulk
+
+
Semiconductor
+
+
Ionized Group
-
-
-
Helmholtz
Double
Layer
Electrolyte
Solid- Electrolyte Junction
Barrier is Formed due to
Transfer of Majority
Carriers from
Semiconductor to
Electrolyte
Major Potential Drop in
Semiconductor Space
Charge Layer.
Only small fraction of Drop
in Electrolyte Region

16. ECPV Cell : Action at Photo electrode
Photo electrode Exposed
Electron-Hole Pairs
Generated in Depletion
Region
E-H Pair Driven Apart by
Electric Field at Interface
(Photo voltage)
Holes react with Electrolyte
and Redox completes at CE
Electrons move from
Photo anode to Counter
Electrode

17. Chopping
2
Current Density ( A/cm )
Photoelectrochemical Cell output parameter
100
0
-600
-400
-200
0
-100
Dark Current
Light Current
2
Dark Current
Light Current
Current Density (A/cm )
200
250
Dark
200
Light
400
600
Voltage (mV)
0
Dark
-250
Light
-500
-750
-1000
-200
-750
-500
-250
0
250
500
Voltage (mV)
The Current–voltage (I–V) characteristic in dark and under light illumination
(a) photovoltaic power output characteristics : Isc=0.05mA/cm2 Voc=250mV
(b) light chopping : n-Type conductivity
(magnitude of voltage increases with negative polarity towards
Zinc Indium Selenide electrode

18. Speed of response and
Transient photoresponse characteristics
20
Voltage
Light
Dark
Chopping
-270
Voltage (mV)
Current (A)
15
10
-275
-280
-285
5
20
40
Time (S)
60
20
40
60
Time(S)
Speed of Response
Photo induced voltage as a function of time

19. Capacitance–voltage (C–V) characteristics
Mott–Schottky plot of PEC cell.

20. Electrochemical Impedance Spectroscopic (EIS) Study
Raw data
Fitted data
3500
3000
-Z'' (Ohm)
2500
2000
1500
1000
500
0
-500
0
2000
4000
6000
8000
10000
Z' (Ohm)
Nyquist plot for ZnIn2Se4 electrode
Equivalent circuit derived
from
Nyquist plot

21. Component values of equivalent circuit
Parameter
(1)
Rs
(2)
R1
(3)
C1
(4)
R2
(5)
Qy2
(6)
Qa2
Value
Error
49 Ω
6.4
1019.19Ω
10743.32
0.002484 F
0.047381
8431.614Ω
11644.95
6.74E-05F
2.54E-05
0.838F
0.0764

22. Conclusion
1. X-ray Diffraction Analysis:
Tetragonal Crystal Structure
2.SEM Analysis :
Homogeneous local edge sharing network structure
3.Optical Absorbance study :
Direct band gap semiconducting material
4. Photovoltaic Power output characteristics:
Photosensitive material
Used as Buffer layer in photovoltaic device
5.Speed of Response and Transient Photo response :
Use of this material as light sensor
Stability of electrode
7.Mott-Schottky plot :
Flat Band Potential : -0.8 V/SCE

23. Acknowledgement
1.Contribution of
Pune University Research Fund under BCUD scheme
2. Motivation of
K.K.Wagh Institute of Engineering Education and
Research, Nasik

24. Thanks
1. ICAER Co-ordination Committee
2. Energy Angels