The Opto Group
One aim of the Opto Group is to develop novel materials for sustainable energy production from solar cells. Interestingly, materials that are suited for one type of optoelectronic application, i.e. solar cells, are frequently well-suited for other applications as well. Accordingly, the Opto Group focuses on light-emitting applications (LEDs) or detectors for photons and ionizing irradiation.
The group explores such applications by characterizing and understanding novel materials with a focus on versatile, emerging perovskite materials which are a promising group of inexpensive, abundant semiconductors.
Highly stable, efficient and reproducible perovskite solar cells
Solar cells based on perovskites are currently one of the most investigated materials for photovoltaics because of the potential for inexpensive, sustainable energy production.
We are focusing strongly on long-term stability of perovskite solar cells believing this is one of the most important topics for a potential commercialized. We developed a new family of perovskites through multiple cation engineering using more stable inorganic cations such as Cs and Rb. The new perovskites have a substantially suppressed amount of detrimental “yellow phase impurities” leading to materials that are more temperature, humidity and phase stable. These compounds enable band gaps for disruptive technologies like perovskite/silicon or perovskite/perovskite tandems.
The developed multicomponent approach is highly investigated because it can create compound materials, similar to alloys, which do not have the disadvantages of the individual components.
Novel materials at the perovskite interfaces
We investigate charge extraction layers at the key interface of the perovskite materials. We demonstrated multiple inexpensive materials using other small molecules and polymers reaching high performances. We introduced the concept of dually functionalized HTMs that transport charge and have other benefits, e.g. perovskite passivation or resistance to metal electrode diffusion. We also studied additive-free polymeric HTMs realizing that perovskites can be stabilized using polymers as a protective barrier.
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