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Light Harvesting

The fabrication of commercially available silicon solar cells typically requires the expensive and energy demanding growth of a single crystalline ingot from a 1420°C hot melt. Hybrid perovskites, in contrast, are inexpensive semiconductors with crystallization temperatures of around 100°C. High-quality thin films can be deposited by slot-die coating, spin-coating, or thermal evaporation. With a direct band gap, a high absorption coefficient and ambipolar diffusion lengths, hybrid perovskites are ideal candidates for novel thin film photovoltaics. Low-cost, flexible photovoltaic devices with efficiencies that rival those of conventional thin-film photovoltaics are already possible.

Their tunable band gap energy also makes perovskites highly attractive for tandem solar cells. By combining a high band gap and a low band gap perovskite thermalization losses can be mitigated. Efficiencies are close to surpass the respective single junctions, and realistic estimates with over 30 % power conversion efficiency are within reach.

The light harvesting sub-group covers a range of inexpensive devices which convert incident photons into other forms of energy. This includes photovoltaics, as well as photo- and X-Ray detectors. Techniques include current-voltage measurements and sensitive external quantum efficiency (EQE) measurements. New deposition approaches include thermal evaporation of halide perovskite films through multi-source depositions. We interact closely with the materials and spectroscopy sub-groups to input new materials and characterise samples.

light harvesting subgroup