Research

– Post-doc (NTNU)

October 2014 – current

My research is currently focused on intermediate band solar cells (IBSCs). In particular, I work on fabrication and characterization of deep level intermediate band materials, namely doped ZnS and Si and Cu2O. I also study reduced MoO3 containing oxygen vacancy defects resulting in formation of filled state within the band-gap. My contributions are pulsed laser deposition of thin films, pulsed laser melting of implanted semiconductors, fabrication of solar cell prototypes, and characterization of thin films and solar cell devices using various relevant techniques.

My duties also include assisting in the training and supervision of PhD and final year project or master students.

In addition to the research activities, I have been the course coordinator and the lecturer for the master level course “Energy and Environmental Physics” at NTNU.

 

 

– Visiting Scholar (IES-UPM)

March 2016 – July 2016 (5 months)

Solar Energy Institute at Technical University of Madrid

 

 

Mohammadreza_nematollahi_PLD_NTNU
Photo by Geir Mogen/NTNU

– PhD (NTNU)

October 2010 – October 2014 (4 years)

Title: Cr-doped ZnS for Intermediate Band Solar Cells  (download abstract)

Trial lecture title: Highly mismatched alloys for optoelectronics. (see the slides here)

 

Pulsed laser deposition of ZnS and transition metal doped ZnS:

(a) The rectangular ablated area on the target showing the X and Y scanning directions. (b) Image of the target, and the visible plasma plume. (c) The film after ablation still on the heater. (d) RHEED pattern of the Si substrate just before the deposition and (e) ZnS film after the deposition.
(a) The rectangular ablated area on the target showing the X and Y scanning directions. (b) Image of the target, and the visible plasma plume. (c) The film after ablation still on the heater. (d) RHEED pattern of the Si substrate just before the deposition and (e) ZnS film after the deposition.
Cross-section SEM image of a single hetero-junction cell with ZnS. The top layer is the Au/Al contact
Cross-section SEM image of a single hetero-junction cell with ZnS. The top layer is the Au/Al contact
Schematic structure of the solar cells studied. (a) A single hetero-junction cell with Cr:ZnS, and (b) with ZnS. (c) A double hetero-junction cell with Cr:ZnS, and (d) with ZnS.
Schematic structure of the solar cells studied. (a) A single hetero-junction cell with Cr-doped ZnS, and (b) with ZnS. (c) A double hetero-junction cell with Cr-doped ZnS, and (d) with ZnS.

– MSc (SUT)

September 2007 – February 2010

Title: The effect of metal oxides on gasochromic properties of WO3 thin films formed by pulsed laser deposition (download abstract)

Supervisor: Prof. Seyed Mohammad Mahdavi

Gasochromic schematic
The optical properties of the gasochromic film changes when exposed to dilute H2 gas. The process is reversible by introducing O2 gas.

 

gas test schematic
Schematic of the gas test experiment.

 

Gasochromic films under dilute H2 gas. The color difference is caused by varying the film concentration.
Gasochromic films under dilute H2 gas. The color difference is due to the presence of Ti, Mo, and Ni cations in the WO3 films.