Research Topic
Improving Thin-Film Solar Cells by Deliberate Interface Tailoring
In recent years, thin film solar cell devices have impressed by their very successful development and fast progress. Today’s thin film photovoltaic systems are on the verge to commercialization, superseding the (more expensive) current state-of-the-art wafer-based Si solar cell technology. However, the next crucial level of performance can only be reached by a knowledge-based optimization, extending current trial-and-error device improvement. Thin film solar cells are composed of a stack of many thin layers of different chemical and electronic structure. Thus, the resulting interfaces can often act as recombination centers when not designed carefully. In most cases, the interfaces not only influence but also determine the local electric fields. Thus, the key issue for a continued fast progress is the knowledge of and the ability to deliberately tailor the electronic and chemical structure at the interfaces in such thin film devices.
To account for the complexity of the current challenges, the Young Investigator Group proposes an interdisciplinary three-pillar approach:
I. Study the performance and the electronic characteristics of the solar cell device.
II. Examination of the initial electronic (e.g., band offsets and charge carrier dynamics) and chemical interface structure.
The information gained from I. and II. is used to elaborate/develop correct models for the investigated “real-world” devices, aiming for the identification of the “unfavorable” (i.e., performance-limiting) interfaces, in order to be finally able to:
III. Recommend and employ deliberate surface/interface modifications to systematically tailor the electronic structure in order to reduce/avoid loss processes.
The goal of the Young Investigator Group is to develop and establish this analysis/optimization approach.
Cross sectional scanning electron micrograph (left) and corresponding scheme (right) of
a Cu(In1-XGaX)(SYSe1-Y)2 – based thin film solar cell. Essential device components together
with respective standard materials and approx. layer thicknesses are given.
