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Hybrid solar cells of semiconductor oxides and conductive polymers have been broadly studied. Poly(3-octylthiophene) (P3OT), is an organic polymer formed by conjugated structures with conductive properties, photoluminescence, a relatively high charge mobility and stability. Zinc oxide (ZnO) has been used as an electron acceptor in this cell type because it offers great electron transport properties, simple manufacturing techniques, non-toxicity, variation and morphologic control. Different ZnO morphologies allow distinct properties in terms of electronic transport in solar cell interfaces. The objective of this paper was to evaluate whether ZnO with its different morphologies can improve the anchorage of P3OT and influence the conductive properties of hybrid solar cells of ZnO/P3OT. ZnO particles were synthetized by co-precipitation with Zn(NO3)2·6H2O in concentrations of 0.05, 0.10 and 0.15 mol L−1. The morphology was evaluated by scanning electron microscopy (SEM), and the suspension was evaluated by thermogravimetric analysis and differential scanning calorimetry and X-ray diffraction. Cells containing the working electrode (ZnO/P3OT) were evaluated by open circuit potential (Voc) and electrochemical impedance spectroscopy (EIS). The SEM images showed three morphologies: spherical ZnO (ZnOE), hexagonal ZnO (ZnOH) and ZnO without defined morphology (ZnOM) due to the variation of the precursor salt concentration. Cells with different morphologies presented medium values of Voc = −0.438 ± 0.027 V. The EIS indicated that ZnOM/P3OT cells have lower values of charge transfer resistance and higher values of capacitance at intermediate frequencies. ZnOM/P3OT solar cells presented the best results in relation to the electron transfer processes.

O poli(3-octiltiofeno) (P3OT) é um importante polímero semicondutor da família dos poli(3-alquitiofenos) (P3ATs), que são potencialmente aplicáveis no campo da optoeletrônica orgânica, nos dispositivos orgânicos emissores de luz (OLEDs) e nas células solares poliméricas (CSPs). Neste trabalho foram estudados, o P3OT e o seu copolímero com a polidifenilamina (PDFA), com o objetivo de definir as melhores condições de síntese eletroquímica para formação de filmes sobre o eletrodo de platina e com as propriedades ópticas e elétricas melhoradas. Os filmes foram preparados a 5 e 18 &730;C em solução de 0,100 mol L-1 LiClO4 ou Et4NBF4 em acetonitrila. Os copolímeros obtidos foram, um sintetizado em camada sobre o substrato, denominado poli(difenilamina-co-3-octiltiofeno) (P(DFA-co-3OT)) e o outro a partir da solução com a mistura dos monômeros chamado de mistura PDFA/P3OT. Os comportamentos eletroquímicos dos filmes gerados foram verificados por Voltametria Cíclica (VC) e caracterizados por espectroscopia de refletância (UV-Vis), Raman, Ressonância Paramagnética Eletrônica (RPE) e Fotoluminescência (PL). Com o auxílio das técnicas eletroquímicas foram definidas as condições de síntese (concentração do monômero e eletrólito, potencial aplicado e tempo de síntese). Por meio dos dados obtidos pelas técnicas espectroscópicas foram caracterizados os segmentos das espécies químicas presentes na matriz do polímero, sendo que os resultados dos espectros Raman conduziram à caracterização de três estruturas (formas aromática, cátion radical e dicátion) que compunham as cadeias dos homo e copolímeros. Os dados de PL, RPE e Raman indicaram que a 77K ocorreu a maior estabilização do cátion radical nos copolímeros. Foram determinados os parâmetros de potencial de ionização (I), afinidade eletrônica (A) e energia de gap (Eg). Os valores de I e A demonstraram a possibilidade da aplicação do material preparado com diferentes interfaces, e para os copolímeros a 5˚C os valores de Eg demonstraram a maior estabilidade dos segmentos cátion radical. Os dados de VC foram utilizados na Espectroscopia de Impedância Eletroquímica (EIE), em que foram comparadas as propriedades resistivas e capacitivas entre os filmes no potencial de circuito aberto (PCA) e potencial de sobretensão (&61544;). Os resultados obtidos pelo diagrama de Bode da EIE foram confirmados com a caracterização por espectroscopia Raman e por meio da microscopia eletrônica de varredura (MEV) foi possível visualizar a mudança na morfologia e espessura dos filmes com as variações de temperatura e eletrólito na síntese. The poly (3-octylthiophene) (P3OT) is an important semiconducting polymer, which are potentially applicable in the field of organic optoelectronics, in organic light-emitting diode (OLED) and polymer solar cells (CSP). In this work we studied the P3OT and its copolymer with diphenylamine (PDFA), in order to define the best conditions of electrochemical synthesis for training films on platinum electrode and with optical and electrical properties improved. The films were prepared 5 and 18 0C in solution of 0.100 mol L-1 Et4NBF4 or LiClO4 in acetonitrile. The copolymers were obtained in a synthesized on the substrate layer, called poly (diphenylamine-co-3-octylthiophene) (P (DFA co-3OT)) and the other from solution by the mixture of monomers called PDFA / P3OT. The electrochemical behavior of the films were checked by cyclic voltammetry (CV) and characterized by spectroscopic reflectance (UV-Vis), Raman, Electron Paramagnetic Ressonance (EPR) and photoluminescence (PL). With the electrochemical techniques have been defined synthesis conditions (concentration of monomer and electrolyte applied potential and synthesis time). Through the data obtained by spectroscopic techniques were characterized segments of the chemical species present in the polymer matrix, and the results of Raman spectra led to the characterization of three structures (forms aromatic, radical cation and dication) that made up the chains of homo and copolymers. The data PL, EPR and Raman indicated by comparing at 298 and 77 K, that occurred at 77K further stabilization of the cation radical in the copolymers. The ionization potential parameters (I), electron affinity (A) and energy gap (Eg) were determined based on the processing of data obtained by CV and UV-Vis spectroscopy. The values of I and A demonstrated the possibility of applying the films prepared with different interfaces and copolymers 5&730;C the values Eg improved due to the greater stability of the segments radical cation. The data CV were used in the Electrochemical Impedance Spectroscopy (EIS), in which we compared the resistive and capacitive properties of the films by open circuit potential (OCP) and potential voltage (&61544;). Results from the Bode diagram of the EIS were confirmed with the characterization by Raman spectroscopy and by scanning electron microscopy (SEM) was possible to visualize the change in morphology and thickness of the films with variations in temperature and electrolyte in the synthesis.