Controlled morphology of electrodeposited CuSCN by

variation of applied bias voltage

ICAER-2013

Presented by SOHAM GHOSH

Dept. Energy Science and Engineering

Outline

• Sensitized solar cell (SSC),

• Motivation of the work,

• Applied bias dependent CuSCN morphology,

• Deposition time dependent CuSCN morphology,

• Application,

• Summary.

2

Dye Sensitized Solar Cell

3

Contains three individual layers

namely: the electron collector, absorber

layer or the dye and the electrolyte or

hole conducting material

e-h pairs separated due the presence

of band-offset at each interface

Easy fabrication; Less energy

consuming

Less pay-back period than Si based solar cell

Efficiency reached > 11% for lab based

devicesDSSC

Semiconductor Sensitized Solar Cell

4

•Dye is replaced by a low band-gap semiconductormaterial leading to an intermediate solid stateDSSC,•Electrolyte is also replaced by a solidsemiconductor making the whole device as a solidstate device.

CuSCN

FTO

ZnO

CdS

Au

ElectronHole

Degradation of dye with time (mainly the UV degradation)

Liquid electrolyte (improper packaging)

Motivation of the work

5

ZnO NanorodsSensitizerCuSCN

Contd.

6

FTO

CuSCN Nanorod

Electron Collector

Ag

Sensitizer

Contd.

• The percolation of hole collecting material into the pores in nanoporous

substrates is quite limited,

• Inverse structural design using p-type semiconductor nanorods as

building blocks,

• Surface area will increase and interface charge recombination will

reduce resulting better charge transport,

• Hole conducting pathway that is likely to be diffusion limited in

comparison to the hoping and grain boundary dominated transport

mechanism.

7

8

SEM images of the CuSCN films deposited at (A) -0.30 V, (B) -0.31 V, (C) -0.32 V, (D) -0.35 V, (E) -0.40 V (F) -0.42 V

Applied Bias Dependent CuSCN Morphology

XRD Pattern of CuSCN

9

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

* *

***

***

(10

7)

(24

1)

(01

5)

(00

6)

(10

1)

Inte

nsi

ty (

a.u

.)

2 Theta (deg.)

-0.30V

-0.31V

-0.32V

-0.35V

-0.40V

-0.42V

(00

3)

(10

4)

*

* FTO Glass

(11

3)

Deposition Time Dependent CuSCN Morphology

10

SEM of time dependant deposition film for (A) 1hr (B) 2hr (C) 3hr

TEM of CuSCN Nanorods

11

Transmission electron microscopy of CuSCN nanorods

Photovoltaic Application

12

Jsc = 8.8 mA/cm2Voc = 0.68FF = 0.63η = 3.9%

Summary

13

• Well shaped nanorods can be deposited under a potential of -0.3V,

• With increasing the applied potential nanorods were started

agglomerated gradually,

• With increasing deposition time the nanorods diameter started to

increase,

• Application for Semiconductor Sensitized Solar Cell.

14

Fabrication Methodology of Copper Thiocyanate

Experimental details:

• Electrolyte contains Cu+2 and SCN- ions in a water-ethanol system

Applied Potential: -0.3 to -0.42 V

Reaction at Cathode:

• Cu(ClO4)2 Cu2+ + 2ClO4-

• NaSCN Na+ + SCN-

• Cu+2 + SCN- CuSCN+

• CuSCN+ + e- CuSCN

15

16

SEM images of the CuSCN films deposited at (A) -0.30 V, (B) -0.31 V

17

SEM images of the CuSCN films deposited at (C) -0.32 V, (D) -0.35 V

18

SEM images of the CuSCN films deposited at (A) -0.40 V, (B) -0.41 V