Stabilization of poly(3-hexylthiophene)/PCBM morphology by hydroxyl group end-functionalized P3HT and its application to polymer solar cells

A new concept to stabilize the morphology of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend through H-bond formation by using a hydroxyl group end-functionalized P3HT (HOC-P3HT-COH) as a compatibilizer is presented. Domain size of the PCBM crystals in the annealed P3HT/PCBM film is diminished with addition of HOC-P3HT-COH. Surface roughness of the P3HT/PCBM film also becomes smoother with addition of HOC-P3HT-COH. Thermal stability of solar cell device is improved significantly through the H-bond formation between HOC-P3HT-COH and PCBM. A high performance and thermal stable polymer solar cell with 4.06% power conversion efficiency under AM1.5G irradiation is fabricated with 5% HOC-P3HT-COH in P3HT/PCBM layer.

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► An end-functionalized P3HT (HOC-P3HT-COH) is used to stabilize morphology of P3HT and PCBM blend.
► HOC-P3HT-COH forms H-bond with PCBM and stabilizes morphology of P3HT/PCBM.
► Domain size of the PCBM crystals in the annealed P3HT/PCBM film is diminished.
► Surface roughness of the P3HT/PCBM film is also decreased.
► Thermal stability of the P3HT/PCBM based devices is also enhanced through the H-bonds formation.