Reliable organic solar cells processed from green solvents

• A small guest molecule in the ideal location makes it possible to generate energy-efficient organic solar cells utilizing eco-friendly solvents.

A record efficiency over 17% is shown. On top of that, solar cells with bigger areas can be generated. "This is a major action towards massive industrial manufacture of reliable and also steady organic solar cells", claims Feng Gao, professor in the Department of Physics, Chemistry and Biology (IFM) at Linkoping University. The result has been released in Nature Energy.

Developments in organic solar cells are rapid, and also the optimum energy effectiveness accomplished by solar cells produced busy is currently over 18%. The energy efficiency determines just how big a portion of the energy in sunlight is transformed to useful energy in the solar cells. The performance restriction is considered to be around 24% for organic solar cells.

One obstacle is to manufacture organic solar cells that are adequately secure to work for ten years or more. Another challenge is that the highest possible energy is attained in solar cells produced in solutions that contain poisonous solvents, with a reasonably low boiling point. The low boiling point causes troubles throughout the manufacture, since the solution vaporizes a little also swiftly. Making use of even more eco-friendly solvents with higher steaming factors leads promptly to a reduction in energy effectiveness. This is a problem that scientists around the globe are working to fix.

These troubles have actually now been fixed in a joint project led by researchers at Linkoping University in Sweden as well as Soochow University in China.

They have actually taken care of to manufacture a solar cell, utilizing a remedy with a high boiling point and also with no harmful ingredients, whose energy efficiency is far better than 17%.

On top of that, the green-solvent refined solar module with a location of 36 cm2 reveals a power conversion performance over 14%. This is the highest possible performance reported to date for organic solar cell modules with an energetic location going beyond 20 cm2. Both of these advancements are important for organic solar cell technology to make its commercial development at a large range.

"Our outcomes currently open for the manufacture of organic solar cells at bigger scales for exterior usage", claims postdoc Rui Zhang, that works with Professor Feng Gao in the Electronic and also Photonic Materials Division, Linkoping University.

The feature of organic solar cells has actually boosted step-by-step. When sunshine in the form of photons is soaked up in an organic semiconducting contributor, an "fired up state" kinds. Electrons leap to a higher energy degree and develop openings at the lower energy degree, to which they are, nonetheless, still drew in. The electrons are not completely freed, and also a photocurrent does not occur. The researchers carried out experiments in which they added different acceptor materials, which accept electrons as well as hence permit them to end up being free, giving rise to a photocurrent.

A number of years back, Chinese researchers developed a brand-new acceptor material, called Y6, which can supply high effectiveness for organic solar cells.

What the job defined in this joint magazine has currently accomplished is to find a guest molecule, referred to as BTO, that makes sure that Y6 molecules in the solar cell are crammed in such a close and steady fashion in the green solvents that the photocurrent can be generated effectively. Including BTO also enables larger locations of the solar cells to be made with high effectiveness.

"Our technique causes clear design rules for optimizing the interaction between organic contributors and also acceptors in multicomponent blends, meeting the critical requirements for future growth of organic photovoltaic technology, states Professor Yaowen Li, Soochow University.