Characterization of CuInSe2 Thin Films for Photovoltaics

Celina S. Dozier

FAMU-FSU:

Dr. Eric Kalu

CMU: Dr. Paul Salvador

Background

What is Photovoltaics?– Process of converting

sunlight into electricity– A potential energy

barrier that separate electrons and holes that are created by the absorption of sunlight

– Creates a current

Substrate

CuInSe2

ZnO

e- Collecting Plate Ni

Semiconducting Materials

Qualities of a good PV material:– Strong light absorption– Low cost– Stability as functions of both time and illumination

conditions– High abundance of source materials– Environmentally friendly technology

Copper Indium Diselenide

Conversion efficiencies of 17.8% have been reached for vapor-deposited CIS cells

The chalcopyrite structure of ternary I-III-VI2 compounds have high absorption coefficients making CIS well-suited for solar cells

Bandgap of 1.02 eV

Experiment

Production Procedure– Nickel is plated on Kapton/Mylar– A three-electrode setup used to deposit CIS

CIS was electrochemically deposited at the following potentials for 5 minutes:

-0.35V, -0.55V, -0.75V, -1.0V, -1.1V How does varying the deposition potential affect the

lattice structure of CIS and surface morphology?

Theoretical X-Ray Pattern

0

200

400

600

800

1000

1200

1400

0 10 20 30 40 50 60 70 80

2 Theta

Inte

nsit

y

-0.75 VCIS TheoreticalNi Theoretical

CIS on Kapton

Mylar Thin Films

AFM Results

Potential: -0.35 V

Unannealed

RMS Roughness: 654Å

Grayscale: 0.5 µm

Potential: -0.55 V

Unannealed

RMS Roughness: 666Å

Grayscale: 0.60 µm

20 µm20 µm

Conclusion

As the deposition potential becomes more negative the roughness increases

The X-Ray patterns of the CuInSe2 films that were grown do not have significant similarities to the theoretical CuInSe2 X-Ray patterns

Acknowledgements

Dr. Eric Kalu Dr. Paul Salvador Graduate students (Andy, Bala, Nitin,

Sukwon, and Pat) CMU Materials Science Engineering

Department