Light management by disordered nano-structures for optoelectronic devices (LAMBDA)

• Applicants: Dr. Karsten Bittkau; Dr.-Ing. Guillaume Gomard
• Subject Area: Synthesis and Properties of Functional Materials ; Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2015 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 278746617

The present proposal falls into the field of light management for optoelectronic thin film devices using 2D planar disordered nano-structures. The latter are designed to act as an efficient scattering architecture whose main goal is to improve the outcoupling properties of white organic light emitting diodes (WOLEDs), and consequently to increase their power efficiency. The methodology and structures developed here will also have direct implications for the field of photovoltaics. Thus, it is planned to test the engineered structures to ameliorate the light-trapping capabilities of amorphous silicon thin-film solar cells, which possess a comparable spectral range of operation as WOLEDs.As a prerequisite for any experimental investigations, a mature fabrication route for the creation of photonic structures with controllable disorder properties will be established using a versatile, large area, wet-chemical technique based on lateral phase separation. In order to optimize the structures produced, a novel optical modeling method will be developed enabling the rigorous calculation of the scattering by a large ensemble of cylindrical scattering centers embedded in a thin film system with low computational resources demands. It will also be used in combination with advanced techniques of scanning near-field optical microscopy to provide further insights into the physical mechanisms at play. The information derived from those analyses will facilitate the integration of the scattering layers into the two targeted devices, and their impact in terms of efficiency increase will be measured.Within the scope of this interdisciplinary experimental/ theoretical study, specific questions related to light scattering by planar pseudo-disordered structures inside thin films systems are addressed, and encompass the influence of those layers on coherent multi-scattering phenomena, on the excitons life time or on the extraction of surface plasmon polaritons.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1839: Tailored Disorder - A science- and engineering-based approach to materials design for advanced photonic applications
• Co-Investigator: Professor Dr. Ulrich Lemmer