The ternary blend films composed of low polymerization degree poly［2

6-(4

4-bis-(2-ethylhexyl)-4H-cyclopenta［2

1-b;3

4-b'］dithiophene)-alt-4

7-(2

1

3-benzothiadiazole)］ (LDP-PCPDTBT)

［6

6］-phenyl-C61-butyric acid methyl ester (PC61BM)

and polymethylmethacrylate (PMMA) were fabricated with and without using 1

8-dibromooctane (DBO) as solvent additive.The role of PMMA was to enable the formation of the smooth and continuous thin films spun from the solution onto the conducting substrate.In addition

the good stability of the PMMA against the heat

oxygen and water attacks was useful for achieving the long lifetime of organic solar cells.The LDP-PCPDTBT and PC61BM phases in the PMMA matrix were amorphous and crystalline

respectively

regardless of the additive processing.The crystalline aggregation of the LDP-PCPDTBT was hampered by the PC61BM molecules

though the additive processing was able to promote the degree of crystallinity of the LDP-PCPDTBT.However

with the additive processing the phase separation of the LDP-PCPDTBT and PC61BM components in the PMMA matrix was optimized

leading to the improved electron-transporting property and thereby an increase of 32.4% in the power conversion efficiency of solar cell

compared to without the additive processing.The current research indicates that the low polymerization degree alternating copolymers can be recycled as efficient electron donors in association with PMMA

helpful for reducing the material cost of organic solar cells.