Improvement of Efficiency of Polymer Solar Cells with Soluble Fullerene Derivatives

Soluble fullerene derivatives, [6,6]-phenyl C₆₁ butyric acid hexyl ester (PCBH) and [6,6]-phenyl C₆₁ butyric acid dodecyl ester (PCBD), were synthesized, and current-voltage (I-V) characteristics of polymer solar cells using these fullerene derivatives were investigated. It is found that PCBH cells show higher short circuit current density (J_sc) than conventional [6,6]-phenyl C₆₁ butyric acid methyl ester (PCBM) cells. J_sc further increases with using high haze TCO substrates and thermal annealing. The efficiency of 3.3%, 3.8% (aperture illumination area were 1.00 cm₂ and 0.25 cm₂, respectively) were obtained. Finally the efficiency of 2.96% (aperture area was 1.001 cm₂) was confirmed by a public test center (AIST, JAPAN)