Photoinduced electron and hole transfer (PIET and PIHT) and thermal charge recombination dynamics (CR) of trilayer thin-films comprising titanyl phthalocyanine (TiOPc), regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) and C60 are studied using flash-photolysis time-resolved microwave conductivity (fp-TRMC) and time-resolved fs-ms transient absorption spectroscopy. Carrier generation following photoexcitation on TiOPc is independently observed at both the P3HT/TiOPc and TiOPc/C60 interfaces, and the trilayer P3HT/TiOPc/C60 structure exhibits enhanced photoconductance signal and longer charge-recombination lifetime relative to the bilayer controls. From pump-probe transient absorption spectroscopy, more detailed carrier generation dynamics was studied. Each bilayer P3HT/TiOPc and TiOPc/C60 exhibited ultrafast electron/hole transfer as well as exciton-diffusion limited processes. Our pump-probe transient absorption results also indicates that following initial charge generation processes to produce P3HT·+/TiOPc—· and TiOPc·+/C60—· at each interface from (P3HT/TiOPc*/C60) via electron transfer and hole transfer processes, the final charge separated product of (P3HT·+/TiOPc/C60—·) is responsible for the long-lived photoconductance signals at fp-TRMC. In this study, we demonstrated that the combination of fp-TRMC and classic pump-probe transient absorption spectroscopy can serve to complement to each other and can be utilized to elaborate charge-generation and recombination dynamics for more complicated ternary cascade heterojunction system

Photoinduced charge transfer and thermal recombination dynamics of a ternary cascade heterojunction composed of poly(3-hexylthiophene), titanyl phthalocyanine, and Buckminsterfullerene

249th National Meeting (2015)

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