The new solar cell comes from the University of Erlangen-Nuremberg and the record breaking solar cell properties apply to a new type of organic, non-fullerene-based single stack solar cells.
An organic solar cell is a form of photovoltaic that deploys organic electronics, formed of conductive organic polymers, for the purposes of light absorption and charge transport in order to produce electricity from sunlight via the photovoltaic effect (the creation of voltage and electric current in a material upon exposure to light and is a physical and chemical phenomenon).
Stacking is a relatively new concept with solar cell technology, albeit a simple on. The step involves stacking different semiconducting materials that collect different frequencies of light, thereby capturing more energy. The concept potentially can lead to efficiencies of up to 50 percent in relation to the stack; whereas conventional solar cells convert less than 25 percent of the energy in sunlight into electricity.
With the new breakthrough, the researchers have achieved a certified energy efficiency of 12.25 percent on an area of one square centimeter. Appropriate stability was demonstrated under various operating conditions, accounting for differences with temperature and sunlight.
According to one of the researchers, Nicola Gasparini: “As the efficiency of a solar cell is proportional to its fill factor, our goal was to increase the fill factor to make them more efficient than they are currently.”
In contrast to using silicon, which itself requires a lot of energy to produce, the polymer layers used in the new solar cells are transferred from a solution directly onto a carrier film, which reduces the energy demand during production and reduces costs. For this, according to EE New Europe, the researchers have sourced an alternate organic molecule that absorbs more light than with established technology. The new material is also very durable.
The main issue with the current model is one of scalability and with avoiding transfer losses when the cell coatings are expanded. This comes down to optimizing the balance of short-circuit current density and open-circuit voltage, which are key factors for obtaining the highest energy yield.
The research has been published in Nature Energy, with the paper titled “Designing ternary blend bulk heterojunction solar cells with reduced carrier recombination and a fill factor of 77%.”
