Minute Torsional Reorganization Elicited Large Visible Range Fluorescence Gain in Terphenyl Derived Crystals

Understanding the variations in the solid-state optical signals of organic semiconductor materials upon subtle structural rearrangement or intermolecular interactions would help to extract the best performance in their electro-optic devices....

Red Carbon: a Carbon-Oxygen-based covalent semiconductor for selective amine sensing

The requirements for organic semiconductor materials and new methods for their synthesis at low temperature have risen over the last decades, especially due to concerns of sustainability. Herein, we present an innovative method for the synthesis of a so-called “red carbon” thin film, being composed of carbon and oxygen, only. This material was already described by Kappe and Ziegler at the beginning of the 20th century, but now can complement the current research on covalent organic semiconductor materials. The herein described red carbon can be homogeneous deposited on glass substrates as thin ilms which reveal a highly ordered structure. The films are highly reactive towards amines and were employed as amine vapor sensors for a scope of analogous amines. The gas-to-solid phase reaction causes a significant change of the films optical properties in all cases, blue-shifting the bandgap and the photoluminescence spectra from the red to the near UV range. The irreversible chemical reaction between the thin film and the vapor was also exploited for the preparation of nitrogen containing thin carbon films. We expect the herein presented red carbon material is of interest not only for sensing applications, but also in optoelectronics.

Study and Analysis of Simple and Precise of Contact Resistance Single-Transistor Extracting Method for Accurate Analytical Modeling of OTFTs Current-Voltage Characteristics: Application to Different Organic Semiconductors

Contact resistance (Rc) characterizes the interface of source-drain electrodes/organic semiconductors and controls the injection efficiency of carriers in organic thin-film transistors (OTFTs). This research paper presents and assesses two methods for extracting the value of the contact resistance from the measured current-voltage characteristics of OTFTs made with various p-type organic semiconductors as active layers. These two methods are the transition voltage method (TVM) and the transfer line method (TLM). The obtained Rc values by the TVM method are in fair agreement with those obtained by TLM, with a maximum percentage of difference around 10%, demonstrating the accuracy of the used transition-voltage method. An analytical model was employed to calculate output characteristics in the linear regime of OTFTs made with various organic semiconductors using the contact resistance values obtained by the transition voltage method. The calculated results are in reasonably good agreement with the experimental ones of each fabricated device, which affirms the ability of the used model to characterize the charge transport correctly in these types of devices. It can be concluded that the used TVM method is not only an easy and practical method, but also a precise way for extracting Rc in OTFTs produced using different organic semiconductor materials.

Diketopyrrolopyrrole Based Organic Semiconductor Materials for Field-Effect Transistors

Over the past several decades, organic conjugated materials as semiconductors in organic field effect transistors (OFETs) have attracted more and more attention from the scientific community due to their intriguing properties of mechanical flexibility and solution processability. However, the device fabrication technique, design, and synthesis of novel organic semiconductor materials with high charge carrier mobility is crucial for the development of high-performance OFETs. In the past few years, more and more novel materials were designed and tested in the OFETs. Among which, diketopyrrolopyrrole (DPP) and its derivatives, as the electron acceptors to build donor-acceptor (D-A) typed materials, are the perspective. In this article, recently reported molecules regarding the DPP and its derivatives for OFETs application are reviewed. In addition, the relationship between the chemical structures and the performance of the device are discussed. Furthermore, an outlook of DPP-based materials in OFETs with a future design concept and the development trend are provided.

Detecting triplet states in opto-electronic and photovoltaic materials and devices by transient optically detected magnetic resonance

Triplet excited states in organic semiconductor materials and devices are notoriously difficult to detect and study with established spectroscopic methods. Yet, they are a crucial intermediate step in next-generation organic...