Crystallization and Phase Segregation Dynamics in Polymer: Fullerene Solar Cells
Imperial College di Londra (UK)
July 20th, 2010
Understanding the length and time scales upon which crystallization and phase segregation occur in polymer:fullerene solar cells is important to better control nanomorphology and therefore device performances. We report studies of the dynamics of crystallization and phase segregation during thermal annealing for a set of materials including poly(3-hexylthiophene) (P3HT), poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b’]dithiophene)-alt 4,7(2,1,3-benzothiadiazole)] (PCPDTBT), poly[(4,4’-bis(2-ethylhexyl)dithieno[3,2-b:2’,3’-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl] (Si-PCPDTBT), as well as fullerenes and corresponding polymer:fullerene blends. We use Grazing Incidence X-ray Diffraction (GIXRD) to monitor crystallization in-situ, and we correlate our observations with several techniques including real time ellipsometry, real time OFET mobilities, differential scanning calorimetry, solar cell performance and molecular dynamics simulations. We conclude that crystallization of the polymer phase is a primary driving force for phase separation and performance optimization in organic solar cells.
Natali Dario Andrea Nicola
Microelectronics and Emerging Technologies