Characterization of CuInSe 2 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 CuInSe 2 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-VI 2 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

CIS on Kapton

Mylar Thin Films

AFM Results Potential: V Unannealed RMS Roughness: 654Å Grayscale: 0.5 µm Potential: V Unannealed RMS Roughness: 666Å Grayscale: 0.60 µm 20 µm

Conclusion As the deposition potential becomes more negative the roughness increases The X-Ray patterns of the CuInSe 2 films that were grown do not have significant similarities to the theoretical CuInSe 2 X-Ray patterns

Acknowledgements Dr. Eric Kalu Dr. Paul Salvador Graduate students (Andy, Bala, Nitin, Sukwon, and Pat) CMU Materials Science Engineering Department