Alongside the news of IMEC and BP Solar’s 18% Mono2 silicon cell efficiency, IMEC has demonstrated a fully solution-processed organic solar cell with a spray-coated active layer and a metal top contact spray coated on top.
The organic cell shows power conversion efficiencies above 3%, a performance comparable to organic solar cells produced by spin coating of the organic layer and vacuum evaporation of the top contact metal. This news marks an important step towards producing organic solar cells with cheap and large-area processes.
[(a) Schematic build-up of the organic solar cell, (b) SEM and (c) FIB/TEM cross sections of the polymer solar cell with a spray coated Ag top contact.]
IMEC is working towards the promise that polymer-based, organic solar cells can achieve low-cost production and a high throughput. However, this can only be attained if all the layers of the cells can be deposited by solution-based, in-line compatible methods. IMEC’s latest research shows that spray coating is a suitable deposition technique, and that it can be used to deposit all layers, including the metal top contact.
IMEC has demonstrated that an active layer — a solution of P3HT and PCBM — deposited with spray coating shows power conversion efficiencies above 3%, a performance that is comparable to that of spin-coated devices.
For the metal top contact, IMEC spray coated a solution with silver nanoparticles. The difficulty lies in achieving this without dissolving the underlying layer, and without damaging it by the temperature needed to sinter the silver nanoparticles.
IMEC demonstrated that spray coating reduces the damage to underlying layers a fair amount compared to other techniques. The company was also able to sinter the silver nanoparticles at 150°C, a temperature that is compatible with processing on flexible substrates.
Tom Aernouts, Teamleader Organic Photovolatics at IMEC said, “R&D on organic solar cells has entered the stage where we can consider low-cost high-volume manufacturing, which is essential for the uptake of this technology by the industry. Our results show that IMEC has the expertise and know-how to play an important role in organic photovoltaics R&D.”