15.1% Efficiency For Polymer Film Based Perovskite

• Toshiba has achieved 15.1% efficiency for 703 cm² large-area perovskite solar module
• It used a newly developed coating method for the perovskite layer as part of a NEDO project
• The new coating process uses improved ink, film drying processes and production equipment to form a uniform perovskite layer over a large area
• It will now aim for 20% or more efficiency on an active area of 900 cm² to further cut manufacturing cost of perovskite PV module to around $0.14 per W

Japanese electronics and engineering firm Toshiba Corporation has reported having achieved 15.1% power conversion efficiency for its 703 cm² large-area perovskite solar module calling it the highest for any large, polymer-film based perovskite PV module.

It was able to achieve this efficiency with the help of a newly developed coating method for the perovskite layer which it claims greatly reduces production time and costs.

Toshiba describes that previously it used a 2-step coating process wherein it first applied a layer of Pbl2 (lead iodide) ink to a substrate, and then a layer of MAI (methyammonium iodide, CH3NH3I) ink. This triggered a reaction that formed a MAPbl3 layer. "However, this multi-step approach had a low coating rate and often left unreacted sections in the perovskite layer," stated the company.

The current efficiency level has been achieved through a 1-step process where it applied MAPbl3 ink directly, but with a new coating method using improved ink, film drying processes and production equipment to form a uniform perovskite layer over a large area. It helped deal with crystallization of MAPbl3 and get a uniform perovskite layer.

"These innovations halve the steps for deposition of the perovskite layer, and raise the coating speed to 6 meters per minute on a 5×5 cm² module, a rate that meets requirements for mass production*3," explained the technology experts of Toshiba.

The company believes this simplified production process will significantly advance towards commercialization of highly efficient, low-cost, polymer film-based perovskite PV modules. It now aims to increase the efficiency to 20% or more on an active area of 900 cm² 'the size required for practical application' which is expected to cut manufacturing cost of perovskite PV module to around $0.14 per W.

It has achieved the new coating technology and perovskite solar modules under the Japanese government's Development of Technologies to Promote Photovoltaic Power Generation as a Main Power Source project of the New Energy and Industrial Technology Development Organization (NEDO).