Enhancing solar cell efficiency to lower overall energy cost
The Sun is a virtually 100 % renewable source of energy that can be exploited by photovoltaics (PV) or solar cells to produce electricity. Relevant technology has advanced tremendously over the past few decades and current research is focused on ways to increase energy conversion efficiency while decreasing costs. The majority of such work is devoted to the development of innovative materials with tuneable optoelectronic properties. While polymer solar cells have drawn broad attention in recent years, one promising class of materials that has been neglected is aniline-based ones. The aniline monomer can be oxidised to produce a variety of different aniline-based polymers with very interesting micro- and nanostructures. The EU-funded project 'Self-organising liquid-crystalline oligoanilines for photovoltaic applications' (SOLICOAPS) applied newly developed synthetic techniques to novel aniline-based self-assembled organic semiconductors. Liquid crystals have unique optical properties and their self-organisation into ordered states between liquid and crystal opens the door to a number of applications. Self-assembled liquid crystalline (LC) semiconductors can yield stacked and aligned architectures that increase charge carrier mobility and is of great interest to the PV community. Scientists focused on LC tetra(aniline) (TANI) compounds. They designed and synthesised novel TANIs and blended them with the photoactive (electron acceptor) materials PC60BM and IC60BA. The first ever LC TANI in a half-oxidised (emeraldine base (EB)) state with novel chemical and electrochemical properties was obtained through materials’ characterisation. Moreover, photoluminescence quenching (an indication of how fast charge transfer occurs) of the C60 electron acceptors by TANI EB derivatives makes these promising for PV applications. SOLICOAPS provided a new route to the design of LC TANIs as a novel class of electron donors for the well known C60 electron acceptors. Highly efficient charge transfer should lead to the development of cost-effective PV technology and widespread market uptake. This will reduce dependence on combustion of fossil fuels and thereby, the associated environmental impact.
