Hole transporting layers in printable solar cells

The incessant evolution of organic and hybrid solar cells has demonstrated that a multilayer architecture is required for an optimum device functioning. Although more attention has been traditionally focused on the active layer materials, it is the interfacial materials, placed between the electrodes and the active region, which might play some of the most critical roles in the solar cell. In this regard, interfacial layers can modulate the compatibility between the electrodes and the active layers in terms of morphology, surface energy or energy level alignment. Furthermore, interfacial layers modulate the light absorption working as optical spacers, assist in the exciton confinement and preserve the active layer from damage or degrada tion. However, the most important role of interfacial layers concerns the charge transport, defining an energy gradient for the selective migration of free charge carriers from the active layer to the electrodes. This chapter offers a comprehensive description of those materials specifically working as hole transporting layers in organic, dye-sensitized and perovskite solar cells. Conjugated polymers, small molecules, metals, metal oxides, self-assembled monolayers, carbon nanotubes and graphene-based materials will be discussed along with their influence on different aspects aimed at the optimization of the solar cell performance

Synthesis and characterization of poly(dimethylsiloxane)-polythiophene composites

The synthesis was performed by the electropolymerization of thiophene on a poly(dimethylsiloxane) (PDMS)-coated platinum electrode at 2.2 V with tetrabutylammoniumtetrafloroborate (TBAFB) as a supporting electrolyte and with acetonitrile as a solvent. The characterization of the PDMS-polythiophene (Pth) composites was carried out with cyclic voltammetry, Fourier transform infrared (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis, and conductivity measurements. The observed conductivities of the PDMS composites were 2.2-5.2 S/cm. The conductivity of Pth did not change appreciably with the addition of up to 30% insulating PDMS, but its processability improved. FTIR, SEM, and DSC studies showed the existence of a strong interaction, rather than physical adhesion, between PDMS and Pth. Highly flexible and foldable PDMS-Pth composites were obtained. (C) 2003 Wiley Periodicals, Inc

Electrochemical preparation and characterization of carbon fiber reinforced poly (dimethyl siloxane)/polythiophene composites: electrical, thermal and mechanical properties

A series of polydimethylsiloxane (PDMS)/polythiophene (Pth)/carbon fiber (CF) composites was synthesized by electrochemical polymerization using tetrabutylammoniumtetrafluoroborate (TBAFB) as supporting electrolyte and acetonitrile as solvent. Composites were characterized by TGA, SEM, and mechanical tests and conductivity measurements. Conductivities of composites were in the range of 25 S/cm. SEM studies show that CF were coated by PDMS/Pth matrix and well oriented in the matrix. In mechanical tests it has been observed that higher percent elongation was obtained by increasing PDMS content whereas tensile strength and modulus of composites increases with increasing CF content