Third-party funded projects

The Fabulous II project aims to uncover the mechanisms behind reduced recombination processes and the influence of dark triplet states in achieving high-performance organic solar cells with non-fullerene acceptors (NFAs) that exhibit fill factors (FFs) exceeding 80%. However, the factors that determine why certain material combinations succeed while others fail remain unclear. Developing a general design rule to address this challenge will be a significant contribution of the project.

The discovery of a two-dimensional electron gas (2DEG) at SrTiO₃/LaAlO₃ interfaces revolutionized oxide heterostructures, enabling spin-orbitronics. However, SrTiO₃ 2DEGs function optimally only at low temperatures, and 2D hole gases (2DHGs) remain elusive. This study explores BaSnO₃-based 2DEGs with high mobility and SrTiO₃/KTaO₃-based 2DHGs to overcome these limitations.

Within the framework of the priority program INtegrated TERahErtz sySTems Enabling Novel Functionality (INTEREST) funded by the German Research Foundation (DFG), terahertz injection locking of Quantum Cascade Lasers (QCLs) with novel, modified Uni-Travelling Carrier (MUTC) photodiodes (PDs) will be developed in cooperation with Universität Duisburg-Essen (UDE, Duisburg), and the Institute of Optical Sensor Systems of the German Aerospace Center (HU/DLR, Berlin).

Within the framework of the priority program INtegrated TERahErtz sySTems Enabling Novel Functionality (INTEREST) funded by the German Research Foundation (DFG), micro-integrated quantum-cascade transceivers for high-resolution spectroscopy and space applications will be developed in cooperation with the "Institute of Optical Sensor Systems" of the Deutsches Zentrum für Luft- und Raumfahrt (DLR), and the Ferdinand Braun Institute (FBH), both located in Berlin.

The emergence of atomically thin two-dimensional (2D) materials and their van der Waals (vdW) heterostructures has sparked new scientific interest, offering unprecedented electronic properties for next-generation technologies. 2D magnets—the latest addition to the 2D family—have unique characteristics that make them ideal for vdW heterostructure designs. 2D magnets have the potential to revolutionize magnetic sensors and spintronic technologies, particularly tunnel magnetoresistance (TMR) devices. However, reliable and tunable TMR devices pose challenges with conventional materials. The MagicTune project aims to address these challenges by controlling spin-polarized tunneling in 2D MTJs through twist angle and gate voltage control, achieving large and tunable TMR at room temperature.

OPVStability aims to identify robust molecular structures and device configurations that enable both efficiency and long-term stability in organic photovoltaics. The project seeks to develop a comprehensive understanding of degradation pathways on molecular level and stability-enhancing factors across materials, interfaces, and morphological aspects. Additionally, it strives to create predictive tools for assessing device longevity and to devise strategies for producing durable organic solar cells.

This research project aspires to make a transformative step away from the established paradigm of few element, simple and single crystalline structures, and towards more complex novel semiconductor materials and hybrid structures. This collaborative project aims at investigating next-generation organic semiconductors for photovoltaics and spintronic applications.

The key objective of this project is the development of integrated terahertz quantum-cascade lasers for high-resolution spectroscopy and future space applications at 3.5 THz and 4.7 THz. These two frequencies are very important for the detection of the OH radical and neutral atomic oxygen, respectively, in atmospheric research as well as in astronomy. The overarching goal is to integrate the QCL chip with optics for optical isolation, outcoupling, and beam shaping as well as an optical fiber.

PDI is currently building up an application laboratory for time-resolved cathodoluminescence spectroscopy, where the detectors will be optimized for ultraviolet wavelengths down to about 180 nm. The system will be capable of measuring classic semiconductor thin-films and heterostructures, 2D materials, as well as 3D nanostructures.

Microcavity exciton-polaritons (polaritons) are light-matter quasi-particles arising from the strong coupling of photons and quantum well excitons in a semiconductor microcavity. Polaritons are composite bosons with µm-sized thermal de-Broglie wavelengths (λdB) of several µm at temperatures of a few Kelvin. A gas of polaritons transitions to a collective single quantum state (an atomic Bose-Einstein-like condensate, BEC) when their λdB exceeds the average inter-particle distance. Own to the long λdB, a polariton BEC can be confined in µm-large intra-cavity traps produced by a lateral modulation of the cavity spacer thickness during the growth process (see figure).