Physics Of Organic Semiconductors Research Articles

Semiconductor Nanostructures for Electronic and Opto‐Electronic Device Applications

During the E-MRS 2019 spring meeting, held in Nice, we organized the 7th installment of the symposium ‘Semiconductor Nanostructures for electronic and opto-electronic device applications’. The symposium covered a broad range of organic and inorganic semiconductor materials, as well as novel (opto-)electronic devices based on such materials. Topical sessions were organized, focused on 0D colloidal nanocrystals, 1D nanowires, and 2D layered materials and quantum wells, as well as their application in light emitting diodes and lasers, photodetectors and solar cells, and electronic devices. To bridge the gap between materials and applications, the symposium also included presentations on light-matter interactions in nanostructured materials. This special section publishes selected papers from the symposium. A feature article is presented by Martinez et al., who discuss recent developments on the use of HgTe colloidal quantum dots for infrared photodetectors (article number 1900449). Original reports are presented on the properties of SnC nanowires (article number 1900590), and Au-decorated Fe2O3 nanostructures (article number 1900589). In addition, methods are discussed to prepare silica and silicon thin films (article number 1900556) and evaluate the contact resistance in four-probe measurements (article number 1900579). Regarding applications, the issue includes the fabrication and characterization of quantum dot-sensitized organic scintillators (article number 1900586). Iwan Moreels was a Ph.D. student and postdoctoral fellow at Ghent University. In January 2012 he joined the Italian Institute of Technology, where he became a tenure track researcher in 2014 and set up the Nanocrystal Photonics Lab. In 2017 he returned to Ghent University as associate professor at the Department of Chemistry. His research is focused on colloidal 2D semiconductor nanocrystals. The broad perspective is to find nanomaterial solutions for different applications, from advanced fluorescent markers to light-emitting devices, sensors and solar energy. Sergio Brovelli is Associate Professor at the Department of Materials Science of the University of Milano-Bicocca and co-founder & chair of the scientific committee of Glass to Power srl. He earned his Ph.D. in Materials Science (2006) at the University of Milano-Bicocca. Before being tenured as Professor of Experimental Physics, he was a postdoctoral Fellow at University College London and Director's Fellow at the Los Alamos National Laboratory. In 2017, he received the National Italian Habilitation for Full Professorship in Experimental Physics. His research group is focused on the synthesis, manipulation and advanced spectroscopy of solution-grown nanostructured functional materials and their application in photonic and optoelectronic devices. Jean-Charles Ribierre is professor at the College of Optical Science and Engineering in Zhejiang University. His research activities focus on the physics of organic semiconductors and their applications in optoelectronic devices, including organic field-effect transistors, organic light-emitting diodes and organic solid-state lasers. His current activities are strongly supported by the Hundred Talents programme of Zhejiang University and the National Natural Science Foundation of China (NSFC). Iván Mora-Seró (Ph.D. Physics 2004) is researcher at Universitat Jaume I de Castelló (Spain). His research is focused on crystal growth, nanostructured devices, transport and recombination properties, photocatalysis, electrical characterization of photovoltaic, electrochromic, and water splitting systems. Recent research activities are focused on new concepts for photovoltaic conversion and light emission (LEDs and light amplifiers) based on nanoscaled devices and semiconductor materials following two main lines: semiconductor quantum dots and lead halide perovskites.

Systematic Study of the PCE and Device Operation of Organic Tandem Solar Cells

By combining optical and drift-diffusion models, a comprehensive simulation of power conversion efficiency of tandem solar cells is presented. To obtain consistent current–voltage characteristics of polymer tandem solar cells, the model takes into account correct description of organic–metal interfaces and organic semiconductor physics, in order to include the effect of interfaces and energetic disorder. A generalized methodology is developed to obtain the current–voltage characteristics of polymer tandem solar cells, which fully accounts for the interplay between the two subcells. The model is applied to the tandem cell with different commercially available polymers and for different subcell thicknesses and interconnection architectures. Based on the results of this model, it will be possible to design and optimize tandem structures toward higher efficiencies. Finally, it is concluded that the parallel configuration shows the highest performance over all studied cell structures.

Theoretical analysis and the morphology control of vertical phase segregation in high-efficiency polymer/fullerene solar cells

The morphology control and optimization in the film-forming process and nanoscale phase separation of donor/acceptor interpenetrating networks played an important role in improving the performance of organic solar cells. Vertical phase separation was defined as an inhomogeneous distribution or concentration gradient of polymer/fullerene blends in the spin-coated film, due to the surface energy of the respective components and their interaction with the substrate or the intermediate buffer layers. In this report, we demonstrated, in detail, the theory of vertical phase separation morphology and control of conventional structure solar cells and inverted configuration solar cells, including the choice of solvents and the drying rate, the surface energy control, thermal annealing, as well as external electric field. In particular, we first proposed internal electronic field model of vertical phase separation and revealed the internal rules and organic semiconductor physics and its mechanism for improving the device efficiency and stability.

Physics of Organic Semiconductors. Edited by Wolfgang Brütting.

Physics of Organic Semiconductors. Edited by Wolfgang Brütting.

Energetic disorder at the metal-organic semiconductor interface

The physics of organic semiconductors is dominated by the effects of energetic disorder. We show that image forces reduce the electrostatic component of the total energetic disorder near an interface with a metal electrode. Typically, the variance of energetic disorder is dramatically reduced at the first few layers of organic semiconductor molecules adjacent to the metal electrode. Implications for charge injection into organic semiconductors are discussed.

Atomic Force Microscopy study of hexagonal boron nitride film growth on 6H‐SiC (0001)

AbstractBoron nitride thin films with their unique mechanical and electrical properties are of interest for various applications and have been grown on a number of different substrates. The cover picture from this issue's Editor's Choice [1] shows an Atomic Force Microscopy topography of a hexagonal BN film grown on 6H‐SiC substrate by Plasma Enhanced Chemical Vapor Deposition at 600 °C. Interesting stress‐relief features developed on the non‐reactive substrate. The corresponding author Kian Ping Loh is Assistant Professor at the National University of Singapore. His research is devoted to the growth of diamond and boron nitride thin films and the fabrication of nanocrystalline diamond and boron nitride nanotubes.As a follow‐up to the recent special issue on ‘Physics of Organic Semiconductors’ [2], Detlef Berner gives insights into organic light emitting diode functioning by coordinated experiment and simulation in his Review Article [3].The present issue also sees the start of our rapid research letters, the fastest peer‐reviewed publication medium in solid state physics. For more information see www.pss‐rapid.com and the Editorial by the Editor‐in‐Chief Martin Stutzmann on page 7 [4].

Special issue: Physics of Organic Semiconductors

This special issue of physica status solidi (a) gives an overview of our present-day knowledge of the physics behind organic semiconductor devices, ranging from the growth of organic layers and crystals, their electronic properties at interfaces, their photophysics and electrical transport properties to the application in organic field-effect transistors, photovoltaic cells and organic light-emit-ting diodes. Guest Editor of the present issue is Wolfgang Brutting, professor at the University of Augsburg, where he leads a research group working on organic semiconductors, their physical and materials properties, and the understanding of the basic processes in these materials and devices. The cover picture is an angular plot of the anisotropy of the charge carrier mobility μ in the a–b plane of a rubrene single crystal, probed on an elastomeric rubber stamp field-effect transistor device. The black and red squares correspond to the values of μ extracted from the linear and saturation regimes of the transistor operation, respectively. More information can be found in the Review Article by R. W. I. de Boer et al. [1].

Physics of Organic Semiconductors

Organic semiconductors are of steadily growing interest as active components in electronics and optoelectronics. Due to their flexibility, low cost and ease-of-production they represent a valid alternative to conventional inorganic semiconductor technology in a number of applications, such as flat panel displays and illumination, plastic integrated circuits or solar energy conversion. Although first commercial applications of this technology are being realized nowadays, there is still the need for a deeper scientific understanding in order to achieve optimum device performance. This special issue of physica status solidi (a) tries to give an overview of our present-day knowledge of the physics behind organic semiconductor devices. Contributions from 17 international research groups cover various aspects of this field ranging from the growth of organic layers and crystals, their electronic properties at interfaces, their photophysics and electrical transport properties to the application of these materials in different devices like organic field-effect transistors, photovoltaic cells and organic light-emitting diodes. Putting together such a special issue one soon realizes that it is simply impossible to fully cover the whole area of organic semiconductors. Nevertheless, we hope that the reader will find the collection of topics in this issue useful for getting an up-to-date review of a field which is still developing very dynamically.