(14s) Photovoltaic Processes

Research Interests: The price of photovoltaic (PV) power only depends on cost per area, power conversion efficiency, and rate of efficiency degradation. The microscopic processes and commercial production processes that give rise to those metrics are diverse, yet intimately connected. Research areas include substrates, transparent conductive contacts, absorbers, buffers, power degradation routes, encapsulation, edge sealant, power storage, and energy storage. My research will ultimately advance each of these 9 aspects through the simultaneous study of processes used to produce the PV devices, processes of their operation, and degradation processes. A deep understanding of each aspect will be necessary for long-term success in PV research, for academics and companies alike. In the near-term, several areas will be attacked: metal micro- and nano-grids for transparent conduction in solar cells, thin film absorber development, and new buffer compounds and deposition processes.

My postdoctoral research has been at the National Renewable Energy Laboratory, where I studied the selenization of Cu-Ga-In precursor films, the most popular industry deposition process for Cu(In,Ga)Se₂ (CIGS) thin film absorbers [1-3]. To investigate very recent world record CIGS power conversion efficiencies that used a potassium fluoride post-deposition treatment, I chose to do the first basic material science study of Cu_1-xK_xInSe₂ (CKIS) alloys [4]. I then used this foundational knowledge to fabricate an officially-measured 15.0%-efficient Cu-K-In-Se solar cell (matching the world record CuInSe₂efficiency, despite being grown at lower temperature, and without the 'gold standard' three-stage co-evaporation process).

My graduate research was at the University of Florida with Tim Anderson, where I studied thermodynamics of the Cu-Ga-In system. That work culminated in a paper that was recently nominated for the Cahn prize [5]. I also studied diverse aspects for halide chemical vapor deposition (CVD) of CIGS: complex chemical equilibrium calculations, finite element method fluid flow simulations of atmospheric pressure CVD, experimental Cu, Ga, and In volatilization by HCl reaction, with supporting empirical and analytical fluid flow modeling, and the first experimental CVD growth of Cu-Se, In-Se, and Cu-In-Se [6].

Teaching Interests: Along with research, I will teach transport, thermodynamics, electrical engineering, materials science classes . Where possible, I will add emphases on thin film growth, semiconductors, electron devices, and photovoltaics.

[1] Muzzillo, C.P., Mansfield, L.M., DeHart, C., Bowers, K., Reedy, R.C., To, B., Noufi, R., Ramanathan, K., Anderson, T.J., (2014) â??The effect of Ga content on the selenization of co-evaporated CuGa/In films and their photovoltaic performance,â? 40th IEEE PVSC Proc., Denver, CO, 1649-1654.

[2] Muzzillo, C.P., Mansfield, L.M., DeHart, C., Bowers, K., Reedy, R.C., To, B., Ramanathan, K., Anderson, T.J., (2015) â??Differences between CuGa/In and Cu/Ga/In films for selenization,â? 42nd IEEE PVSC Proc., New Orleans, LA, 1-6.

[3] Muzzillo, C.P., Mansfield, L.M., Ramanathan, K., McGoffin, J.T., Sites, J.R., Anderson, T.J., (2016) â??Photovoltaic properties of selenized CuGa/In films with varied compositions,â? 43rd IEEE PVSC Proc., Portland, OR, in press.

[4] Muzzillo, C.P., Mansfield, L.M., Ramanathan, K., Anderson, T.J., (2016) â??Properties of Cu_1-xK_xInSe₂ alloys,â? Journal of Materials Science, 51(14), 6812-6823.

[5] Muzzillo, C.P., Campbell, C.E., Anderson, T.J., (2016) â??Cu-Ga-In thermodynamics: Experimental study, modeling, and implications for photovoltaics,â? Journal of Materials Science, 51(7), 3362-3379.

[6] Muzzillo, C.P., (2015) â??Chalcopyrites for solar cells: chemical vapor deposition, selenization, and alloying,â? Dissertation, Chemical Engineering, University of Florida, Gainesville, FL.