Direct Band Gap Measurements J Ryan Peterson Thanks

Direct Band Gap Measurements J. Ryan Peterson Thanks to: Dr. John S. Colton (advisor) Kameron Hansen, Luis Perez, Cameron Olsen

Quantum Dot Synthesis Band gap distribution due to core size distribution Different core sizes

Direct Band Gap Transitions

Varying band gap energy: Brus Equation Pb. S quantum dot band gap Bulk Pb. S band gap

Pb. S Photoluminescence 398 nm Diode Laser Spectrometer Sample

Pb. S Photoluminescence Signal adjusted for system sensitivity Measured signal Half max Measured signal

Size and Band Gap Results Sample Measured Radius Expected Band Gap (Brus equation) Measured Band Gap and FWHM Aerobic Sample 1 2. 25 ± 0. 48 nm 1. 70 e. V (1. 29 e. V - 2. 50 e. V) 1. 33 e. V (0. 33 e. V) Aerobic Sample 3 3. 03 ± 0. 39 nm 1. 12 e. V (. 97 e. V – 1. 35 e. V) 1. 14 e. V (0. 31 e. V) Anaerobic Sample 3 3. 04 ± 0. 54 nm 1. 12 e. V (. 92 e. V – 1. 46 e. V) 1. 23 e. V (0. 23 e. V) Anaerobic Sample 6 5. 70 ± 0. 89 nm 0. 61 e. V (. 56 e. V -. 69 e. V) 1. 0 e. V (0. 3 e. V) Aerobic Sample 6 6. 10 ± 0. 89 nm 0. 59 e. V (. 54 e. V -. 65 e. V) < 1. 0 e. V

Ferritin: protection against photocorrosion

Thioglycerol-capped Lead Sulfide Photocorrosion Thioglycerol-capped Pb. S Ferritin-enclosed Pb. S

Thioglycerol-capped Lead Sulfide Photocorrosion

Conclusions and Future Work • Ferritin core size and band gap widely tunable • Ferritin effectively protects against photocorrosion • Future work will investigate the band gap of zinc oxide using photoluminescence

Future work: Measuring zinc oxide band gap

Measurement limits Detector Response Signal adjusted for system sensitivity Half max Measured signal