The influence of molecular weight distribution on the optimal thermal treatment of poly(3-hexythiophene) based bulk heterojunction photovoltaic cells

Chlorobenzene cast films of poly(3-hexylthiophene)-blend blend-[6,6]-phenyl C-61 butyric acid methyl ester (P3HT-blend-PCBM) in 1:1 ratios were used in photovoltaic cells with the structure glass/ITO/PEDOT-blend-PSS/P3HT-blend-PCBM/LiF/Al. By varying the molecular weights of the P3HTs from 4500 to 280 000 g mol mol(-1), it was found that P3HT molecular weight distributions had an, important impact on cell characteristics and the most effective annealing temperature required.