Built-in Flaw Identified

Built-in Flaw Identified

Author: ChemistryViews

Polymeric solar cells have an efficacy of around 3 %, compared to 15–20 % of other solar technologies. Harald Ade and co-workers, North Carolina State University, USA, report that this is due to the structure of the solar cell themselves.

By using resonant soft X-ray scattering, the team studied the interfacial width of the heterojunction at a variety of annealing temperatures. Photoluminescence quenching measurements showed a three-fold increase in the number of excitons dissociated with annealing at over 140 °C. However, device performance was observed to systematically decrease with annealing.

Monte Carlo simulations revealed that a significant portion of the energy is lost due to the inefficient charge separation associated with increased interface roughness. The team conclude that heterojunction sharpness is a requirement for high performance devices.


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