Secondments at the Ecole Polytechnique Fédérale De Lausanne (EPFL)
Rashmi Runjhun, NaMeS PhD student, paricipated in the secondments at the Institut Des Sciences Et Ingénierie Chimiques, Laboratory Of Photonics And Interfaces. She provided her research work in the distinguished lab of Prof. Michael Graetzel at EPFL Switzerland. Rashmi Runjhun mostly focused on fabrication of solar cell devices using perovskite materials. At EPFL, initially, she learned the several techniques and instruments involved in the device fabrication and characterization of solar cells. These included substrate cleaning, solution preparation methods, spin coating, spray pyrolysis, thermal evaporation and I-V measurements. After learning the techniques, Rashmi worked on the device fabrication involving various perovskite and electron transporting materials. Simultaneously, she also carried out the optimization of films based on lead free 2-D perovskite powders, which she had synthesized at IPC PAS. Rashmi optimized the films by using different solvents, concentrations, spinning speeds, annealing temperature and annealing times. The films with best properties were further used for making devices. She also fabricated solar cells based on lead perovskites materials with double cations in cooperation with Dr. Daniel Prochowicz. In order to synthesize this system they developed a new route by changing one of the precursors. They studied the thickness and quality of perovskite films by varying the concentration of perovskite solution, amount of precursors, spinning speed, annealing temperature as well as annealing time. Using the new precursors and with optimized film parameters, they found that devices based on this perovskite system gave very high efficiency compared to the conventional double cation perovskite. They achieved a power conversion efficiency of more than 20 % for the best device.
Working at EPFL was extremely beneficial and motivating for Rashmi research project. In the duration of six months, she learned the actual device fabrication process and the characterization of solar cells using world-class experimental facilities. She also learnt how to use the perovskite materials for solar cell application and what properties needs to be optimized for better device performance. It gave her a very good idea of the approach that she need to follow for her future research.
1 Nov, 2017.-26 Apr., 2018
Ecole Polytechnique Fédérale De Lausanne (EPFL), Switzerland