A5071977383- Organic Electronics and Photovoltaics
- Molecular Junctions and Nanostructures
- Conducting polymers and applications
- Perovskite Materials and Applications
- Organic Light-Emitting Diodes Research
- Semiconductor materials and interfaces
- Advancements in Semiconductor Devices and Circuit Design
- Plant Diversity and Evolution
- Thin-Film Transistor Technologies
- Advanced Memory and Neural Computing
- Plant Taxonomy and Phylogenetics
- Marine and coastal plant biology
- Spectroscopy and Quantum Chemical Studies
- Quantum Dots Synthesis And Properties
- Photochemistry and Electron Transfer Studies
- Fullerene Chemistry and Applications
TU Dresden
2017-2021
Philipps University of Marburg
2014
Abstract Organic photodetectors have promising applications in low-cost imaging, health monitoring and near-infrared sensing. Recent research on organic based donor–acceptor systems has resulted narrow-band, flexible biocompatible devices, of which the best reach external photovoltaic quantum efficiencies approaching 100%. However, high noise spectral density these devices limits their specific detectivity to around 10 13 Jones visible several orders magnitude lower near-infrared, severely...
We present organic near-infrared photodetectors based on the absorption of charge-transfer (CT) states at zinc-phthalocyanine–C60 interface. By using a resonant optical cavity device architecture, we achieve narrowband detection, centered around 1060 nm and well below (>200 nm) gap neat materials. measure transient photocurrent responses wavelengths 532 1064 nm, exciting dominantly materials or CT state, respectively, obtain rise fall times few nanoseconds short circuit, independent...
Organic solar cells with an electron donor diluted in a fullerene matrix have reduced density of donor-fullerene contacts, resulting decreased free-carrier recombination and increased open-circuit voltages. However, the low concentration prevents formation percolation pathways for holes. Notwithstanding, high (>75%) external quantum efficiencies can be reached, suggesting effective hole-transport mechanism. Here, we perform systematic study hole mobilities 18 donors, at ∼6 mol % C60, varying...
Charge carrier recombination in organic disordered semiconductors is strongly influenced by the thermalization of charge carriers density states (DOS). Measurements dynamics, conducted under transient or steady-state conditions, can easily be misinterpreted when a detailed understanding interplay and missing. To enable adequate measurement analysis, we solve multiple-trapping problem for recombining analyze it steady excitation paradigm different DOS distributions. We show that rates...
A blend of a low-optical-gap diketopyrrolopyrrole polymer and fullerene derivative, with near-zero driving force for electron transfer, is investigated. Using femtosecond transient absorption electroabsorption spectroscopy, the charge transfer (CT) recombination dynamics as well early-time transport are quantified. Electron ultrafast, consistent Marcus-Levich-Jortner description. However, significant unusually short excited (S1 ) CT state lifetimes (≈14 ps) observed. At low S1 -CT offset,...
We employed bias-assisted charge extraction techniques to investigate the transient and steady-state recombination of photogenerated carriers in complete devices a disordered polymer-fullerene blend. Charge is shown be dispersive, with significant slowdown rate over time, consistent results from kinetic Monte Carlo simulations. Surprisingly, our experiments reveal little no contributions early time nonequilibrated properties. conclude that energetic relaxation outpaces any nongeminate under...
The performance of organic solar cells is limited by trap states, which increase energetic disorder, lead to trap-assisted recombination charge carriers, and lower carrier mobility. To solar-cell efficiency, it important understand the origin distribution those states. Using impedance spectroscopy, authors find that intermixing C${}_{60}$ donor molecule DCV5T-Me in bulk heterojunction introduces notably deep electron-trap states phase, decreasing power-conversion efficiency. As a widely used...
A theoretical description for recombination kinetics of charge carriers in a disordered system with broad energy distribution localized states (DOS) is suggested. This governed by the exchange between transport and traps. Concentration transients systems Gaussian DOS, typical organic semiconductors, appear much steeper than those obtained exponential DOS. difference caused thermalization these two types DOS functions. The comparison mobile trapped might help to distinguish possible shapes...
Abstract Perovskite solar cells (PSCs) have attracted great interest over the past few years due to their outstanding power conversion efficiencies. However, operational stability still needs be improved for broad commercial application. A commonly observed phenomenon PSCs is hysteresis in current–voltage characteristics, which has been suggested related issues with long‐term stability. thorough understanding of processes involved may also guide way further improving cells’ We fabricate...
Abstract Intrinsic organic small molecule and polymer materials are insulators. The discovery that polymers can be made highly conductive by doping has therefore sparked strong interest in this novel class of conductors. More recently, efficient also been achieved is now a key technology the multi-billion dollar light emitting diode industry. Nevertheless, comprehensive description charge transport presence still missing for semiconductors with localized electronic states. Here, we present...
The history of Rhipsalis agudoensis N.P. Taylor, originally and erroneously thought to be from Southern Brazil (Rio Grande do Sul, Agudo), its discovery in South-eastern Rio de Janeiro São Paulo states, is documented. Images the recently found locations are provided.
Organic semiconducting materials are typically subject to energetic and positional disorder localization of electronic states. The behavior these therefore strongly influenced by thermalization charge carriers in the localized density states (DOS). Consequently, non-equilibrium processes play an important role operation devices made such materials. We show as example that measurements recombination dynamics, conducted under transient or steady-state conditions, can easily be misinterpreted...