Characterization of CuInSe2 Thin Film Solar Cells

Chukwuemeka Shina Aofolaju 1 Advisors: Dr. Eric Egwu Kalu 1 Dr. Paul Salvador 2

By

1. FAMU – FSU College of Engineering

2. Carnegie Mellon University

Research Background

● Cost of Crystalline Silicon versus Fossil fuel electricity generation.

● CIS thin films require less semiconductor material

● They are potentially lighter and thinner than Silicon Solar Cells

● CIS would be relatively inexpensive

CIS – Copper Indium Diselenide

Hypothesis &Experimental Methods

● Hypothesis: CIS deposition conditions influence the CIS film microstructure (atomic composition, film morphology) - affect of electrolyte flow rate

● Experimental Methods● Atomic Force Microscopy

● Views the surface profile of both CIS

● X-ray Diffraction

● Crystal structure and crystal orientation of the thin film particles

● Scanning Electron Microscope (sample atomic composition)

Method of CIS Deposition● Substrate materials PET &

Kapton.

● Electroless Nickel is deposited on substrate

● CIS Deposited on Electroless Nickel (non-recirculated and circulated bath)

Rate (%) Time (s) Volume (ml) Rate (ml/s)40 20.54 10.2 0.550 19.38 12 0.6260 20.38 14.6 0.7270 18.78 16 0.85

PET - poly(ethylene terephthalate)

AFM Scan Results

50 µm 20 µm

50 µm

Annealed CIS

Unannealed CIS Unannealed Samples

Size: 50 umRoughness: 297 AGrayscale: 400 AFlow rate: 0.72 ml/s

Size: 50 umRoughness: 334 AGrayscale: 540 AFlow rate: 0.85 ml/s

Annealed SamplesSize: 50 umRoughness: 194 AGrayscale: 140 AFlow rate: 0.72 ml/s

Size: 50 umRoughness: 206 AGrayscale: 140 AFlow rate: 0.85 ml/s

50 µm

50 µm

X-ray Diffraction

● Understand the molecular and material structure of the thin films

● Monitor peaks and compare them to theoretical CIS scans

● Note the differences or variation in peaks as flow-rate changes.

● Scan annealed samples and see differences in peaks.

XRD scan results

CIS 601B

0

5000

10000

15000

20000

25000

30000

0 10 20 30 40 50 60 70 80

2 theta

Inte

nsity

Unannealed & Annealed CISCIS samples

0

5000

10000

15000

20000

25000

30000

10 20 30 40 50 60 70

2 theta

Inte

nsity

Annealed

Unannealed

Result & Discussion

● Peaks are present but are neither at the same angle of the theoretical CIS scans or intensity

● CIS scans are similar to substrate scans (Mylar and Kapton)

● Nickel scans are also similar to that of Mylar and Kapton

● CIS not Crystalline.

SEM Results

● Copper – 19.16 %● Selenium – 41.72 %

● SEM Results show the presence of Copper and Selenium but no Indium. X-ray Diffraction analysis might not be the best way to characterize our samples OR Annealing factors should be changed to show crystalline structures.

Conclusion & Future Goals

● Learned how to use the Atomic Force Microscope to view surface morphology of thin films

● Studied the use of X-ray Diffractormeter and used it to characterize sample

● Change the Annealing factors and find other methods to characterize samples.

● Experiment through more flow rates.

Acknowledgements

● CMU/FAMU PREM Program● Dr. Salvador and grad students● Dr. Eric Kalu● Miss Celina Dozier