Energy harvesting with hybrid photovoltaics
Heterojunction solar cells consisting of an organic electron donor and an inorganic oxide semiconductor have attracted much attention over the past decade. In such cells, conjugated polymers absorb photons and inorganic materials are used as the acceptor and electron transporter in the structure. An effective approach to building hybrid heterojunctions is to infiltrate the organic polymer in an oxide nanotube array (NTA). Efficient infiltration from a polymer solution with a high molecular weight into the NTA host can be challenging. In the EU-funded project 'Development of inorganic / organic hybrid heterojunction solar cells' (HYBRIDSOLAR2010), scientists exploited the intrinsic electroactivity of a monomer precursor molecule to electrochemically infiltrate the polymer into the NTA in situ. To present the feasibility of this approach, scientists used the PEDOT polymer and the titanium dioxide (TiO2) NTA. Careful selection of the synthetic parameters allowed fine-tuning of both composite composition and morphology. By optimising all key processes (light absorption, exciton generation and charge transport), hybrids with improved photoelectrochemical properties were prepared to eventually fabricate novel solar cell devices. Work was also geared towards developing ternary hybrid assemblies based on TiO2, PEDOT and cadmium sulphide (CdS) for solid-state quantum-dot-sensitised solar cells. By using the successive ionic layer adsorption and reaction method, scientists deposited the CdS and cadmium selenide quantum dots on the nanotubes and then grafted the PEDOT polymer. The photoelectrochemical deposition of the conducting polymer was carried out through selective excitation of the chalcogenide sensitiser and the collective photoexcitation of the two semiconductor components. Through selecting suitable organic and inorganic materials, HYBRIDSOLAR2010 made important progress in fabricating hybrid solar cell devices. Project results were published in many peer-reviewed journals.
Keywords
Energy harvesting, heterojunction solar cells, organic electron donor, inorganic oxide semiconductor, nanotube array
