A team of researchers from the Shanghai Institute of Optics and Fine Mechanics and Soochow University claimed that the introduction of diiodooctane (DIO) additives could enhance the efficiency of nano-scale polymer solar cells (PSCs).

The researchers said that polymer solar cells have the advantages of light-weight, low-cost fabrication, and mechanical flexibility. However, polymer solar cell’s low power conversion efficiency is a significant barrier to its large-scale application, they added.

In its report, the researchers stated that several methods had been developed to control the nanomorphology of the active layer of polymer solar cells, including post-annealing, solvent treatment, interfacial buffer layer, and solvent additives. Out of this, the use of solvent additives with high boiling points like 1,8- DIO is one of the most convenient and simple methods suitable for large-scale manufacture and compatible with flexible substrates.

“DIO has been proved to be an effective method to control the bulk nanomorphology and the surface composition of the bulk heterojunction (BHJ) layers,” said the researchers. Nanomorphology is defined as the morphology of nano-scale materials. Morphology is a shape, optical appearance, or form of phase domains in substances like polymers, polymer blends, crystals, and composites.

In their report, the researchers stated that the introduction of DIO additives could enhance the lifetime of polaron pairs in the donor material that could benefit the photocarrier generation. Besides that, the introduction of DIO additives in bulk heterojunction film can improve the charge transfer excitons and free charge generations.

“Our experimental results reveal the underlying mechanism of DIO in effective photocarrier generation, which leads to the higher efficiency of photovoltaic, which can provide an effective route to enhance the efficiency of nano-scale polymer solar devices,” the researchers said.

In October 2020, a team of researchers from the Oak Ridge National Laboratory and the University of Tennessee claimed that they had developed a process to slow phonos – the waves that transport heat, which could enhance the efficiency of hot-carrier solar cells.