Researchers at Hiroshima University in Japan have created a type of solar cell that improves power efficiency and electricity generation by mixing various polymers and molecular semiconductors as light-absorbing materials. These types of solar cells, known as organic photovoltaics (OPVs), are devices that generate electricity when light strikes their light absorbers. The efficiency of a solar cell is determined by comparing the amount of electricity generated to the amount of light incident on the cell. This is called "photon harvesting," which measures how many light particles are converted into electric current. The higher the efficiency of a solar cell, the more economical and practical its commercial applications become.
A research team at the Graduate School of Advanced Science and Engineering added only a small amount of a compound that absorbs long-wavelength light, producing an OPV that is 1.5 times more efficient than the version without the compound. This compound enhances absorption intensity due to optical interference effects within the device. The team further points out that how these fuels are distributed is key to further improving power generation efficiency.
The paper's corresponding author, Itaru Osaka, published in the journal Macromolecules in November 2020, said, "We added a very small amount of sensitizing material to the OPV battery, which consists of semiconductor polymers and other materials that we had previously developed."
"This leads to a significant increase in photocurrent, which in turn improves power conversion efficiency due to amplified photon absorption caused by the light interference effect. The key is to use a very special polymer that allows us to provide a very thick semiconductor layer for OPV cells, which significantly enhances the light interference effect compared to a thin layer."
As for future work, Osaka is focusing on promoting the development of the most advanced solar cells.
"Our next step is to develop better semiconductor polymers as the host material for this type of OPV, as well as better sensitizing materials that can absorb more photons in the longer wavelength region. This will enable OPV cells to achieve the highest efficiency in the world."
Adding organic pigments to perovskites can improve battery stability and efficiency.
A research team in Florida is studying solar cells that combine new and old materials.
Chemistry professor Biwu Ma and his team have published a new study showing that adding a small amount of existing organic pigments to perovskite solar cells can improve the cell's stability and efficiency.
This study was published in the journal Angewandte Chemie.
“The pigments are abundant, inexpensive, and robust,” Ma said. “When we combine them with perovskite, we can create new, high-performance hybrid systems. It combines the old with the new, and together they create something exciting.”
Ma's research on next-generation solar cell technology has focused on solving the stability problems and challenges of perovskite solar cells. Perovskite solar cells are a type of photovoltaic cell that contains perovskite-structured compounds, most commonly organic-inorganic lead or tin halide-based hybrid materials, as the light-collecting layer.
Research on perovskite solar cells has progressed rapidly over the past decade. When first reported in 2009, the power conversion efficiency was about 4%, now it is as high as 25%. However, commercial viability also has drawbacks, such as the material's tendency to degrade rapidly.
Researchers around the world have been searching for the perfect formula that makes them both stable and effective.
Ma's research team conducted experiments using methylammonium lead iodide. Without the pigment layer, the efficiency of the solar cells was 18.9%. With it, this figure rose to 21.1%. The research team also found that, under ambient conditions, the unencapsulated cells could retain 90% of their initial efficiency after the addition of the pigment layer.
Adding a layer of insoluble pigment through simple solution treatment and heat annealing also makes the cells hydrophobic, meaning that water cannot remain on the surface.
“We believe that using low-cost pigments to passivate the surface of these batteries is a very promising approach to improving battery stability and efficiency,” Ma said.
