Understanding Organic Solar Cell Energy Loss Technology
Organic solar cells are a promising new technology that may be more attractive for urban or facade applications than the common silicon solar panel, as they can be lightweight, flexible and display a range of colors.
However, as scientists try to understand the fundamental mechanisms behind how organic solar cells work, further improvements in device performance have been slow.
A new method of expressing the energy loss in organic solar cells has now been developed by engineers from princeton university and King Abdullah University of Science and Technology.
This description has been expanded to include suggestions for designing the best devices and could change the way organic solar cells are typically built. November 18e2022, Joule published their work.
There was a traditional way of describing and defining energy loss in organic solar cells. And it turns out that description wasn’t quite right.
Study Co-Author Barry Rand, Associate Professor, Electrical and Computer Engineering, Princeton University
Rand argued that the conventional way of describing energy loss did not account for the existence of disorder in an organic solar cell. Dynamic disorder is a type of disorder that results from erratically moving molecules at the microscopic level, which virtually guarantees a loss of energy at most temperatures.
The other type, structural or static disorder, results from the internal arrangements of the components that make up an organic solar cell and the intrinsic structures of those components.
Regardless of the materials used, previous research on organic solar cells has produced values of around 0.6 electron-volts without accounting for the mess in energy loss calculations.
However, when Rand and his team took disorder into account when calculating energy loss and testing various devices, they found that the degree of disorder had a significant impact on the amount of energy lost by a organic solar cell.
Rand added:As the disorder of a solar cell increases, we see our non-radiative energy loss component – the component over which we have control – grow rapidly. The non-radiative energy loss increases with the square of the disorder component.”
Researchers were able to suggest materials that minimize clutter and, therefore, result in more efficient devices after demonstrating that increased clutter leads to a large increase in energy loss in devices. In an organic solar cell, scientists have some control over the degree of structural disorder because they can select the materials they use and how to arrange them.
When designing an organic solar cell, scientists can focus on producing a homogeneous mixture of materials, in which the components of a film are all crystalline or amorphous, or a heterogeneous mixture, in which the components of a film are both crystalline and amorphous.
Through their research, Rand’s team has proven that homogeneous mixtures are the best choice for creating organic solar cells. Rand advised against combining highly crystalline and highly amorphous materials in a single device to create higher performance organic solar cells.
“If you have something in between, heterogeneity in which parts of a film are slightly crystalline and some parts are amorphous, that’s when you lose the most energy.Rand said.
This result departs from conventional wisdom, which held that a certain degree of heterogeneity in solar cell mixtures was advantageous for overall performance. But Rand said his team’s finding that mixtures of heterogeneous devices exhibited high levels of disorder and lost a significant amount of energy could give researchers a new direction as they work to develop more organic solar cells. effective.
Rand added:Heterogeneity has often been at the center of the devices. A certain level of crystallinity was considered beneficial. But it turns out that’s not what we saw.”
He observed that many of the best organic solar cells on the market today are made of highly amorphous films and suggested that, given the limitations of current technology, completely amorphous mixtures are more practical than those that are crystalline.
Although the primary goal of his team’s research was to understand how organic solar cells work, Rand is optimistic that others will be able to use their findings to create more efficient gadgets and eventually set new performance standards for this. promising solar technology.
Rand concluded:This discovery is another aspect of organic solar cells that we can add to what we already know, which will help us improve their efficiency in the future.”
Besides Rand, other authors include Jules Bertrandie, Anirudh Sharma, Wejdan Alsufyani, Julien F. Gorenflot, Frédéric Laquai and Derya Baran of King Abdullah University of Science and Technology. Saeed-Uz-Zaman Khan, a former electrical and computer engineering graduate student who is now at ASML, and Manting Gui of Princeton University are also contributors.
The U.S. Department of Energy’s Office of Basic Energy Sciences and King Abdullah University of Science and Technology’s Office of Sponsored Research supported the research.
Khan, S.-U.-Z., et al. (2022) Quantification of the effect of energy disorder on the energy loss of organic solar cells. Joule. doi:10.1016/j.joule.2022.10.012