Transparent Electrodes for Efficient Optoelectronics
November 15th, 2019 MONICA MORALES-MASIS MESA + Insitute, University of Twente

In this presentation we discuss the status and recent developments in the field of transparent contact materials for efficient optoelectronics devices, with special focus on transparent conductive oxides (TCOs) for solar cells. The implementation of TCOs that combine exceptionally low optical absorption from the UV to the IR with high lateral conductivity is crucial to avoid parasitic absorption or electrical losses in solar cells. The interfaces between the TCO and the adjacent device layers should ensure minimum contact resistance and light in-coupling need to be optimized, by for example tuning of the refractive index of the TCO electrode. The main challenge for developing high-performance TCOs, is to fulfill simultaneously many, if not all of these requirements, with their final properties being driven by the inherent trade-off between the electrical and optical properties. Hydrogen-doped and zirconium-doped In2O3 TCOs are leading the race of the ideal transparent electrodes for solar cells, mainly due to their exceptionally high electron mobility (> 100 cm2/Vs) that can be achieved at low deposition temperatures (< 200 °C), their wide band gap (between 3.5 and 3.9 eV) and their low sub-bandgap absorption. These properties are strongly linked to a low density of defects, which results from a high crystalline quality and passivated grain boundaries. Here we compare these high mobility TCOs, from their fundamental properties to their integration in semitransparent hybrid halide perovskite solar cells for tandem devices. We furthermore present recent efforts to reduce or replace indium in TCOs while keeping optimal optoelectronic properties. This by applying material design or controlled synthesis from amorphous up to epitaxial growth. Finally, we discuss how lessons learned in the oxides field can be applied to develop new non-oxide p-type transparent materials and halide perovskite solar cell absorber materials.

Seminar, November 15, 2019, 12:00. ICFO’s Seminar Room

Hosted by Prof. Valerio Pruneri