Extensive research effort over the last decade as well as excellent optoelectronic properties enabled perovskite photovoltaics (PV) to exceed 25% power conversion efficiency (PCE). As record PCEs have so far been only demonstrated for laboratory scale solar cells, several key challenges remain unsolved and have to be tackled in order to bring the technology to industrial maturity for its commercialization. The instability of the photoactive perovskite absorber material to environmental factors such as oxygen, moisture, UV light and elevated temperatures pose a particularly critical challenge.

In this regard, a multitude of encapsulation strategies has been employed to prevent degradation. Conventional encapsulation is mostly relying on glass-glass-packaging of the devices, utilizing various thermo- or UV-curable encapsulant adhesives and edge sealants to ensure hermeticity during prolonged field exposure. Despite great progress, chemical reactivity with perovskites, incompatible processing conditions, insufficient mechanical stability or too high water vapor permeability of adhesives and sealants still hinders optimal long-term stability. A potential solution presents the application of hermetic laser sealing of glass frits (see Figure 1), being an established process in the smartphone manufacturing industry. Glass frit encapsulation is providing excellent hermeticity in regard to moisture and oxygen, accordingly, first results showed a very promising retention of device performance over 500h. However, in-depth optimization of process parameters as well as contacting layouts has to be performed in order to compete with obtained PCEs of other encapsulation approaches. Furthermore, the application for state-of-the-art layer stacks has still to be proven, current results being based on HTL-free perovskite solar cells.

Figure 1. Schematics of the glass frit encapsulation approach employed for a perovskite solar cell. Previously deposited and sintered glass frit on both encapsulating glass substrates is brought in contact and soldered utilizing a laser beam.

In order to get familiar with the topic, the scope of work includes a short literature review regarding the current state of the art. Setting optimal preconditions, the employed laser setup is then calibrated. Subsequently, experiments are designed and conducted to obtain optimal laser sealing parameters based on quantitative results. The work concludes with the application of the encapsulation approach to perovskite solar modules and the characterization of their long-term performance.

The facilities of the Institute of Microstructure Technology, Light Technology Institute and Institute of Applied Materials (Applied Material Physics) will provide a perfect environment for insights in interdisciplinary work between physics, mechanical and electrical engineering. The candidate will get the opportunity to work in a young and highly motivated international team and will get precious experience.

We are looking for a candidate with a strong affinity for development and experimental work. The ideal candidate should have a strong drive to engage with research activity that often implies addressing novel challenges. Prior lab experience will be advantageous.  This is a multidisciplinary project, so a will to broaden horizons and strengthen a diverse set of skills is also desirable.

Contract's duration: 6 Months

Starting date: May 2022         

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