Layers of poly(3-hexylthiophene), PHT, phenyl vinyl thiophene, PVT3, poly(p-phenylene-2,3′-bis(3,2′diphenyl)-quinoxaline-7-7′-diyl), PPQ, and covalently linked porphyrin-fullerene donor-acceptor dyad, P-F, were deposited as various multilayer films, which then were used to study photoinduced electron transfer and photocurrent generation. The aim of the research was to clarify functioning of different energy and electron donating and accepting layers in charge transfer processes, which were initially created in a film consisting of parallel P-F molecules. The reactions were studied by means of time-correlated and steady-state fluorescence, time-resolved photovoltage, and electrochemical photocurrent measurements. The longest-lived charge-separated state and the highest efficiency of photocurrent generation were obtained for the multilayer structure of PHT|PVT3|porphyrin-fullerene. Porphyrin-fullerene dyads deposited parallel as the Langmuir -Blodgett film transfer electrons from porphyrin to fullerene yielding radical cation and anion moieties, respectively. The dyad on a PHT layer induces electron donation from PHT to the porphyrin cation. When PVT3 is deposited between the PHT and the P-F layers, it promotes both energy and electron transfer to the porphyrin moiety of the dyad, retards the recombination of the primary charge-separated state, and thus increases the photocurrent generation. PPQ was used as an electron acceptor from the fullerene radical anion, causing an increased lifetime of the charge separation.

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The organization of pi-pi stacking perylenediimide (PDI) derivative, PDI12, was studied in solution and in thin films. Films were prepared with the Langmuir-Schaeffer (LS) method and characterized by means of AFM, optical profilometry, steady-state absorption, emission, fluorescence lifetime, and transient photovoltage measurements. The columnar aggregates observed previously in PDI12 solutions and in spin-coated films persist also in LS films. Because of the specific conditions during the preparation of the LS film, i.e., hydrophobic interactions and lateral compression, the columnar aggregates seem to organize with their long axis perpendicular to the layer plane whereas in spin-coated films the columns were oriented parallel to the layer plane. According to AFM and profilometer results, the thickness of LS monolayer of PDI12 is 10 nm, indicating that it consists mainly of aggregates, each containing approximately 30 monomers. Intermolecular photoinduced energy and electron transfer processes in C(60)|PDI12 double layer junction were studied. The fluorescence lifetime of PDI12 film is exceptionally long, but the quenching is very efficient in the presence of C(60). In charge transfer studies, long-lived photovoltage signal was observed for the double layer. Results of this work indicate that PDI12 acts as an electron acceptor and fullerene C(60) as an electron donor.

Photoinduced intra- and intermolecular electron transfer (ET) in thin films of porphyrin-fullerene dyad (P-F) and perylenetetracarboxidiimide (PTCDI) was studied by means of photoelectrical and spectroscopic methods. Films consisting of smooth 100 mol% layers of P-F and PTCDI were prepared by the Langmuir-Schäfer (LS) technique and thermal evaporation, respectively. The time-resolved Maxwell displacement charge (TRMDC) and laser flash-photolysis methods were utilized to demonstrate photoinduced ET from P-F to PTCDI regardless of which chromophore is photoexcited. Finally, the information about the electron movement in the respective thin films was used to build a layered organic solar cell, whose internal quantum yield (Φ(I)) of collected charges was 13%.