Abstract
Hybrid devices based on silicon nanowires dispersed in poly(hexylthiophene: P3HT) thin films have been realized. The different steps, starting from the production of n type silicon nanowire, dispersion of the organic-inorganic components in solution to produce hybrid thin films, which have been integrated in simple photovoltaic diode structures, have been developed. The n type doping of the nanowires is indicated by Raman spectroscopy whereas their crystalline structure is shown by HRTEM. A broadening of the silicon absorption spectrum towards the near infrared is induced by an electronic confinement effect for nanowire diameters of the order of 10 nm. Effective dissociation of the photogenerated charge pairs is shown by a partial quenching of P3HT photoluminescence with increasing SiNWs content, whereas an open circuit voltage of 0.68 V is deduced from the electrical characteristics under visible light illumination. However photocurrents remain low for the investigated material combinations. The high series resistance appears the most critical point limiting the device performances. The high densities of SiNWs electronic surface states acting as trapping centers can account for the large reverse current. To confirm the high potential of this new type of hybrid films for energy conversion, improvements are needed for a better control of the silicon nanowire/polymer interface, which appears the critical point.