Ph.D Thesis

Ph.D StudentTzabari Lior
SubjectStudy of the Physical Processes in Photovoltaic Cells
Containing Organic Material
DepartmentDepartment of Electrical and Computer Engineering
Supervisor PROF. Nir Tessler


Converting the solar energy into electrical power is one of the main challenges humanity faces today. Solar cells, which are the main candidate for this mission, are already in the market and under extensive use. While the inorganic solar cells currently in use are very efficient (about 20-25% power conversion efficiency), they require high cost and high energy consumptive processes. Showing efficiencies of more than 11%, the Organic Photovoltaic Cells (OPV’s) hold the promise of being a low cost, easy to produce and flexible alternative for the inorganic ones .

To improve the OPV’s efficiency even further, we must better understand the physical processes ruling the cell’s behavior. Unfortunately, searching the literature, it is very difficult to achieve such understanding. Different mechanisms are pointed out as the limiting ones, most probably due to the different measuring concepts and the varied working points that are used. Moreover, the consequence of changing one of the fabrication processes or material parameters, and the reasons for it, are frequently debated.

We have developed a unique technique enabling separation of the different mechanisms taking place in the cell one from the other, and quantifying the parameters that govern them . Being able to do so, we can compare devices with various configurations and understand the physical reasoning for their different behavior . We hope that the gained knowledge will facilitate the way for rational deign of better and improved OPV’s, and for a greener future to us all.