Visualizing and controlling optoelectronic processes in lead halide perovskites
Event details
| Date | 20.10.2016 |
| Hour | 16:30 › 17:30 |
| Speaker |
Dr. Alexander Weber-Bargioni Lawrence Berkeley National Laboratory |
| Location | |
| Category | Conferences - Seminars |
Visualizing and understanding electronic and opto-electronic processes at their native length scale will enable unprecedented control over material functionality. This insight is specifically critical to identify the precise photo physical processes and loss mechanisms in light harvesting materials or to identify novel properties and functionality in quantum confined materials.
In the first part of my seminar I will report what we found when visualizing local opto-electronic processes critical for power conversion efficiency in lead halide perovskites. Photovoltaic devices based on hybrid perovskite materials have exceeded 22% efficiency within only a few years of research and are assumed to operate homogeneous throughout the material. We visualized the photo-current and photo voltage generation with 10 nm spatial resolution using photo current microscopy and near field optics and find surprisingly an enormous inter and intra-grain heterogeneity, which provides insight on how to optimize perovskite PV materials towards the theoretical limit.
In the second part of my seminar I will show how insight into the local opto-electronic processes enabled us to make alternative opto electronic devices and explore novel optoelectronic functionalities: We used micron sized single crystal perovskites acting as both cavity and gain medium, to make these single crystals lase in quasi continuous wave mode or electrically contact them to create LEDs with high external quantum efficiency. In collaboration with Prof. Buonsanti’s group we reduced the size of the perovskite crystals to the quantum-confined regime and assembled them in 2-D, and found record exciton diffusion length of over 2 um, mediated by Foerster Resonant Energy Transfer.
Practical information
- Expert
- Free
Organizer
- Prof. Ulrich Lorenz
Contact
- Prof. Ulrich Lorenz