Elucidating understanding and realising device improvements in halide perovskite tandem cells through construction of a high-throughput characterisati

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Perovskite solar cells (PSCs) have rapidly become the most promising emerging photovoltaic technology. Less than a decade since their inception, PSCs have already achieved power conversion efficiencies comparable to silicon solar cells, the current market leader. This rapid development can be explained by the excellent optoelectronic properties of lead halide perovskites, such as high absorption coefficients and long carrier diffusion lengths, facile synthesis routes yielding high quality material and the possibility to tune material properties, such as the bandgap, by compositional engineering. Bandgap tuning makes it possible to make a perovskite tandem solar cell, where two sub-cells with a different bandgap perovskite are stacked on top of each other, allowing more efficient harvesting of the solar spectrum.Single junction PSCs have been studied using a wide range of techniques and device physics are increasingly well understood. This is much less the case for tandem devices, in part because research interest is only building now, but mainly because of the increased complexity of these device systems. The number of layers and interfaces is more than doubled, making design and understanding of photonic in-coupling and electronic charge collection a technical challenge, but one of paramount importance. In addition, processes in one of the sub-cells often cannot be studied fully independently from the other sub-cell.As fabrication and measurements are very time consuming, typically a minimal amount of samples is studied. This has led to contradictory and poorly reproducible reports in literature. In this project we aim to develop new high-throughput electronic and optical characterisation methods and use these to further our understanding of the energetic and photonic properties of tandem PSCs.ObjectivesObjective 1: Design and build a high-throughput setup to study optoelectronic processes at individual interfaces in tandem devices under operation.Objective 2: Measure fundamental electrical properties of tandem PSCs using the custom-built setup and study how these properties evolve under operating conditions (bias and illumination).Objective 3: Simulating device behaviour including photonic structures to maximise light absorption and device performance.