Organic cell based on additive-based coating solution achieves 16.27% efficiency

Scientists from the Korea Institute of Science and Technology (KIST) have used a dielectric additive in organic photovoltaic fabrication to produce uniform films in ambient humidity levels between 10% and 70%. The researchers said the approach improves process stability for organic solar cells.

Researchers from the Korea Institute of Science and Technology have developed a new dielectric additive-based coating technology for organic photovoltaics.

The team found their modification allows organic photovoltaics to be manufactured reliably regardless of changes in seasonal humidity, helping to overcome the sensitivity to humidity traditionally displayed during organic PV manufacturing.

The researchers’ work involved introducing a low-cost dielectric additive, carvone (CV), into the photoactive layer solution. The CV formed a non-covalent complex with the organic acceptor material (L8-BO) that enhanced forming uniform crystallites of acceptors and exciton dissociation in D18:N3:L8-BO blend. 

The addition of CV also induced strong inward Marangoni flows during blade coating, the researchers explained, enabling homogeneous morphology over large areas. The Marangoni effect consists of a flow driven by local differences in interfacial tension caused by temperature or concentration gradients.

Through the modification, the researchers were able to create uniform photoactive films under ambient relative humidity ranging from 10% to 70%.

Under testing, large-area organic photovoltaic cells featuring the CV-based process achieved a power conversion efficiency of 16.27% on a module measuring 20.33 cm2 in size. The researchers claim this is among the highest efficiencies achieved in organic solar modules above 20 cm2 and compares to an efficiency of 15.1% for a cell fabricated under conventional methods.

The researchers calculated a variation in efficiency across seasons within ±2%, lower than the typical deviation observed in commercial-grade solar panels. They said their modification also brings cost benefits by removing the need for costly dry room facilities, with manufacturers able to mix the additive into existing coating solutions and use current equipment without modification.

Hae Jung Son, leader of the research, commented that the technology “offers a scalable path toward low-cost, stable, and high-performance solar energy production.” 

“We are now expanding this approach to tandem solar modules and seeking collaboration with industrial and global research partners,” Son added.

The accompanying research paper, “Dielectric additive enables humidity-independent preparation of blend morphology for high-performance, large-area organic photovoltaics,” is available in the journal Joule.