Dorothea Scheunemann
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View article: Universal Soft Coulomb Gap Governs Thermoelectric Performance in Doped Conjugated Polymers
Universal Soft Coulomb Gap Governs Thermoelectric Performance in Doped Conjugated Polymers Open
Although consensus exists that the thermoelectric properties of doped organic semiconductors result from a complex interplay between a large number of mutually dependent factors, there is no consensus on which of these are dominant, or eve…
View article: A Universal Soft Upper Limit to the Seebeck Coefficient in Organic Thermoelectrics
A Universal Soft Upper Limit to the Seebeck Coefficient in Organic Thermoelectrics Open
View article: Size-Dependent Charging Energy Determines the Charge Transport in ZnO Quantum Dot Solids
Size-Dependent Charging Energy Determines the Charge Transport in ZnO Quantum Dot Solids Open
Building up a solid-state material from quantum dots (QD), which are often referred to as artificial atoms, offers the potential to create new materials with unprecedented macroscopic properties. The investigation of the electronic propert…
View article: Two‐Step Design Rule for Simultaneously High Conductivity and Seebeck Coefficient in Conjugated Polymer‐Based Thermoelectrics
Two‐Step Design Rule for Simultaneously High Conductivity and Seebeck Coefficient in Conjugated Polymer‐Based Thermoelectrics Open
The trade‐off between enhancing conductivity (σ) through doping while concurrently observing a reduction in the Seebeck coefficient ( S ) presents a key challenge in organic thermoelectrics. Here, a two‐step structural design strategy is d…
View article: Is the field of organic thermoelectrics stuck?
Is the field of organic thermoelectrics stuck? Open
With the rising popularity of organic thermoelectrics, the interest in doping strategies for organic semiconductors has increased strongly over the last decade. Here, we use aggregate data to discuss how far the approaches pursued till dat…
View article: Electrically Programmed Doping Gradients Optimize the Thermoelectric Power Factor of a Conjugated Polymer
Electrically Programmed Doping Gradients Optimize the Thermoelectric Power Factor of a Conjugated Polymer Open
Functionally graded materials (FGMs) are widely explored in the context of inorganic thermoelectrics, but not yet in organic thermoelectrics. Here, the impact of doping gradients on the thermoelectric properties of a chemically doped conju…
View article: Spontaneous Modulation Doping in Semi‐Crystalline Conjugated Polymers Leads to High Conductivity at Low Doping Concentration
Spontaneous Modulation Doping in Semi‐Crystalline Conjugated Polymers Leads to High Conductivity at Low Doping Concentration Open
The possibility to control the charge carrier density through doping is one of the defining properties of semiconductors. For organic semiconductors, the doping process is known to come with several problems associated with the dopant comp…
View article: Equilibrium or Non‐Equilibrium – Implications for the Performance of Organic Solar Cells
Equilibrium or Non‐Equilibrium – Implications for the Performance of Organic Solar Cells Open
With power conversion efficiencies approaching 20%, organic solar cells can no longer be considered the ugly duckling of photovoltaics. Successes notwithstanding, there is still a need for further improvement of organic solar cells, both r…
View article: Preparation and Structural Characterization of Thin Films of CuInS<sub>2</sub> by Sintering Colloidally Synthesized Nanoparticles at Moderate Temperature
Preparation and Structural Characterization of Thin Films of CuInS<sub>2</sub> by Sintering Colloidally Synthesized Nanoparticles at Moderate Temperature Open
Copper indium disulfide nanoparticles continue attracting attention as absorber material in light harvesting devices. The preparation of thin films by deposition of this material from colloidal solution remains challenging. Typically, coll…
View article: Charge transport in doped conjugated polymers for organic thermoelectrics
Charge transport in doped conjugated polymers for organic thermoelectrics Open
Research on conjugated polymers for thermoelectric applications has made tremendous progress in recent years, which is accompanied by surging interest in molecular doping as a means to achieve the high electrical conductivities that are re…
View article: Delocalization Enhances Conductivity at High Doping Concentrations
Delocalization Enhances Conductivity at High Doping Concentrations Open
Many applications of organic semiconductors require high electrical conductivities and hence high doping levels. Therefore, it is indispensable for effective material design to have an accurate understanding of the underlying transport mec…
View article: On the Origin of Seebeck Coefficient Inversion in Highly Doped Conducting Polymers
On the Origin of Seebeck Coefficient Inversion in Highly Doped Conducting Polymers Open
A common way of determining the majority charge carriers of pristine and doped semiconducting polymers is to measure the sign of the Seebeck coefficient. However, a polarity change of the Seebeck coefficient has recently been observed to o…
View article: Sequential doping of solid chunks of a conjugated polymer for body-heat-powered thermoelectric modules
Sequential doping of solid chunks of a conjugated polymer for body-heat-powered thermoelectric modules Open
Sequential doping of 1 mm3 sized cubes of regio-regular poly(3-hexylthiophene) (P3HT) with 2,3,5,6-tetrafluoro-tetracyanoquinodimethane is found to result in a doping gradient. The dopant ingresses into the solid material and after two wee…
View article: High Thermoelectric Power Factor of Poly(3-hexylthiophene) through In-Plane Alignment and Doping with a Molybdenum Dithiolene Complex
High Thermoelectric Power Factor of Poly(3-hexylthiophene) through In-Plane Alignment and Doping with a Molybdenum Dithiolene Complex Open
We report a record thermoelectric power factor of up to 160 μW m-1 K-2 for the conjugated polymer poly(3-hexylthiophene) (P3HT). This result is achieved through the combination of high-temperature rubbing of thin film…
View article: Rubbing and Drawing: Generic Ways to Improve the Thermoelectric Power Factor of Organic Semiconductors?
Rubbing and Drawing: Generic Ways to Improve the Thermoelectric Power Factor of Organic Semiconductors? Open
Highly oriented polymer films can show considerable anisotropy in the thermoelectric properties leading to power factors beyond those predicted by the widely obeyed power law linking the thermopower S and the electrical conductivity σ as S…
View article: Non-Wiedemann-Franz behavior of the thermal conductivity of organic semiconductors
Non-Wiedemann-Franz behavior of the thermal conductivity of organic semiconductors Open
Organic semiconductors have attracted increasing interest as thermoelectric converters in recent years due to their intrinsically low thermal conductivity compared to inorganic materials. This boom has led to encouraging practical results …
View article: Experimentally Validated Hopping-Transport Model for Energetically Disordered Organic Semiconductors
Experimentally Validated Hopping-Transport Model for Energetically Disordered Organic Semiconductors Open
Charge transport in disordered organic semiconductors occurs by hopping of charge carriers between localized sites that are randomly distributed in a strongly energy-dependent density of states. Extracting disorder and hopping parameters f…
View article: Watching Space Charge Build Up in an Organic Solar Cell
Watching Space Charge Build Up in an Organic Solar Cell Open
Space charge effects can significantly degrade charge collection in organic photovoltaics (OPVs), especially in thick‐film devices. The two main causes of space charge are doping and imbalanced transport. Although these are completely diff…
View article: Impact of a Doping-Induced Space-Charge Region on the Collection of Photogenerated Charge Carriers in Thin-Film Solar Cells Based on Low-Mobility Semiconductors
Impact of a Doping-Induced Space-Charge Region on the Collection of Photogenerated Charge Carriers in Thin-Film Solar Cells Based on Low-Mobility Semiconductors Open
Unintentional doping of the active layer is a source for lowered device\nperformance in organic solar cells. The effect of doping is to induce a\nspace-charge region within the active layer, generally resulting in increased\nrecombination …
View article: Effect of Imbalanced Charge Transport on the Interplay of Surface and Bulk Recombination in Organic Solar Cells
Effect of Imbalanced Charge Transport on the Interplay of Surface and Bulk Recombination in Organic Solar Cells Open
Surface recombination has a major impact on the open-circuit voltage\n($V_\\text{oc}$) of organic photovoltaics. Here, we study how this loss\nmechanism is influenced by imbalanced charge transport in the photoactive\nlayer. As a model sys…
View article: Chiral Excitonic Organic Photodiodes for Direct Detection of Circular Polarized Light
Chiral Excitonic Organic Photodiodes for Direct Detection of Circular Polarized Light Open
A facile route to soft matter self‐powered bulk heterojunction photodiode detectors sensitive to the circular polarization state of light is shown based on the intrinsic excitonic circular dichroism of the photoactive layer blend. As light…
View article: Ligand-free preparation of polymer/CuInS<sub>2</sub> nanocrystal films and the influence of 1,3-benzenedithiol on their photovoltaic performance and charge recombination properties
Ligand-free preparation of polymer/CuInS<sub>2</sub> nanocrystal films and the influence of 1,3-benzenedithiol on their photovoltaic performance and charge recombination properties Open
Modification of ligand-free polymer/CuInS2 absorber layers led to improved solar cell performance and charge carrier lifetimes.
View article: Schottky Solar Cells with CuInS 2 Nanocrystals as Absorber Material
Schottky Solar Cells with CuInS 2 Nanocrystals as Absorber Material Open
Colloidal semiconductor nanocrystals with tunable optical properties are promising materials for light harvesting in solar cells. So far, in particular cadmiumand lead chalcogenide nanocrystals were intensively studied in this respect, and…
View article: The effect of polymer molecular weight on the performance of PTB7-Th:O-IDTBR non-fullerene organic solar cells
The effect of polymer molecular weight on the performance of PTB7-Th:O-IDTBR non-fullerene organic solar cells Open
Activation energy for charge transport, carrier concentration and recombination rate are identified to strongly affect the device characteristics.
View article: Charge carrier loss mechanisms in CuInS<sub>2</sub>/ZnO nanocrystal solar cells
Charge carrier loss mechanisms in CuInS<sub>2</sub>/ZnO nanocrystal solar cells Open
The charge carrier loss mechanisms in solution-processed CuInS2/ZnO nanocrystal solar cells are studied using steady-state and transient techniques. The results represent a step forward in understanding the device physics of cop…
View article: Investigation of the Spatially Dependent Charge Collection Probability in CuInS<sub>2</sub>/ZnO Colloidal Nanocrystal Solar Cells
Investigation of the Spatially Dependent Charge Collection Probability in CuInS<sub>2</sub>/ZnO Colloidal Nanocrystal Solar Cells Open
Solar cells with a heterojunction between colloidal CuInS$_2$ and ZnO\nnanocrystals are an innovative concept in solution-processed photovoltaics, but\nthe conversion efficiency cannot compete yet with devices employing lead\nchalcogenide …