The weak intermolecular interactions inherent in organic semiconductors make them susceptible to defect formation, resulting in localized states in the band-gap that can trap charge carriers at different timescales. Charge carrier trapping is thus ubiquitous in organic semiconductors and can have a profound impact on their performance when incorporated into optoelectronic devices. This review provides a comprehensive overview on the phenomenon of charge carrier trapping in organic semiconductors, with emphasis on the underlying physical processes and its impact on device operation. We first define the concept of charge carrier trap, then outline and categorize different origins of traps. Next, we discuss their impact on the mechanism of charge transport and the performance of electronic devices. Progress in the filed in terms of characterization and detection of charge carrier traps is reviewed together with insights on future direction of research. Finally, a discussion on the exploitation of traps in memory and sensing applications is provided.

/pdf/charge-carrier-traps-in-organic-semiconductors-a-review-on-1s9up4phic.pdf

Charge carrier traps in organic semiconductors: a review on the underlying physics and impact on electronic devices

Organic photodetectors (OPDs) have attracted continuous attention due to their outstanding advantages, such as tunability of detecting wavelength, low-cost manufacturing, compatibility with lightweight and flexible devices, as well as ease of processing. Enormous efforts on performance improvement and application of OPDs have been devoted in the past decades. In this Review, recent advances in device architectures and operation mechanisms of phototransistor, photoconductor, and photodiode based OPDs are reviewed with a focus on the strategies aiming at performance improvement. The application of OPDs in spectrally selective detection, wearable devices, and integrated optoelectronics are also discussed. Furthermore, some future prospects on the research challenges and new opportunities of OPDs are covered.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/advs.202002418

Recent Progress in Organic Photodetectors and their Applications.

This work was from King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under award nos. OSR-2018-CARF/CCF-3079 and OSR-2019-CRG8-4095.3. F.A. acknowledges the support from The Wilkinson Charitable Foundation. C.M. acknowledges financial support from the Swedish Research Council (grant no. 2018-03824) and the Knut and Alice Wallenberg Foundation through a Wallenberg Academy Fellowship Prolongation grant.

Doping Approaches for Organic Semiconductors

Organic photodetectors with UV-sensitivity are of great potential for various optoelectronic applications. Integration of high charge carrier mobility, long exciton diffusion length as well as unique UV-sensitivity for active materials is crucial for construction of UV-sensitive devices with high performance, however, very few organic semiconductors can integrate these properties simultaneously. Herein, two novel organic semiconductors containing large steric hindrance triphenylamine groups, 1,6-distriphenylamineethynylpyrene (1,6-DTEP) and 2,7-distriphenylamineethynylpyrene (2,7-DTEP) are designed and synthesized. It demonstrates that the single crystals of both 1,6-DTEP and 2,7-DTEP exhibit superior integrated optoelectronic properties of high charge carrier mobility, unique UV absorption, high photoluminescence quantum yields as well as small exciton binding energies. Organic phototransistors constructed using 1,6-DTEP and 2,7-DTEP single crystals show ultrasensitive performance with ultra-high photoresponsivity of 2.86 × 106 and 1.04 × 105 A W-1 , detectivity (D*) of above 1.49 × 1018 and 5.28 × 1016 Jones under 370 nm light illumination, respectively. It indicates the great potential of 1,6-DTEP and 2,7-DTEP-based phototransistors for organic UV-photodetector applications and also provides a new design strategy to develop series of better performance UV photoelectric organic materials for related research in organic optoelectronics.

Organic UV-Sensitive Phototransistors Based on Distriphenylamineethynylpyrene Derivatives with Ultra-High Detectivity Approaching 1018.

The pentafluorosulfanyl (SF5) moiety is a lesser known and underutilized functional group that displays high electronegativity, chemical and thermal stability, and low surface energy, among other useful properties. Despite being around for almost 60 years, practical application of the unique SF5 group in various areas of chemistry has only recently picked up, which is mostly due to longstanding challenges associated with its synthetic accessibility. While most of the latest attention involving the use of SF5 has been in medicinal chemistry, it has also started to feature much more frequently in functional materials design, especially in the area of optoelectronic materials. This review will describe the ways in which the distinctive properties of SF5 have been harnessed to tune the optoelectronic character of different classes of functional materials, starting with the earliest examples from the late 1990s to the intensive research efforts in recent years.

Pentafluorosulfanyl group: an emerging tool in optoelectronic materials

This paper reports a UV-sensing organic field-effect phototransistor with a stacked pentacene channel and a doped aggregation-enhanced emission (AIE)-fluorescent electret for potential applications, such as photomemory storage and photodetectors. It is found that the emission of the photoirradiated doped electret (PA-SMX and PI-SMX) layer can be manipulated at various doping levels, which can be further absorbed by the photoactive pentacene channel. These photogenerated excitons can be separated, and the electrons can be trapped into the electret layer in the presence of gate voltage bias. Therefore, the photoinduced programming and electric field-driven erasing effects of the designed memory device based on doped electrets exhibit optimal photomemory performance with a memory window (MW) of 37.2 V and a reliable retention time over 10 000 s with good cyclic endurance. The photodetection can also be modulated by the illumination power intensity, which reflects a photosensitivity (S) of 1.92 × 106 and a photoresponsivity (R) of 45 A W−1 for organic phototransistors with the PI-SM5 doped electret at a photoexcitation intensity of 720 μW cm−2 at 365 nm. The photoresponse following the change in the threshold voltage and photocurrent correlate well with the spectroscopic results and provide further understanding and optimization of organic phototransistor memory devices.

UV-sensing organic phototransistor memory devices with a doped organic polymer electret composed of triphenylamine-based aggregation-induced emission luminogens

The synthesis and characterization of a pair of pentafluorosulfanylated styrenic polymers and their subsequent application in nonvolatile organic field-effect transistor (OFET) memory devices are reported. The unusual pentafluorosulfanyl (SF5) functional group is unique in that it possesses a strong dipole moment that arises from both inductive and resonance effects but is at the same time highly hydrophobic. This intriguing chemical moiety also presents steric bulk that is comparable to a tert-butyl group. Exploiting these intrinsic physicochemical properties, the use of pentafluorosulfanylated styrenic polymers as the electret layer of nonvolatile OFET-based memory devices is reported. Aside from being the first examples of SF5-functionalized styrenic polymers, the reported materials also display excellent thermal stability, moderately large memory windows and retention times, and stable reversibilities spanning multiple PGM/ERS cycles.

Pentafluorosulfanylated polymers as electrets in nonvolatile organic field-effect transistor memory devices

https://www.jabc.or.kr/journal/download_pdf.php?doi=10.3839/jabc.2023.028

Anti-inflammatory effects of Lycoris chejuensis callus using biorenovation

https://www.jabc.or.kr/journal/download_pdf.php?doi=10.3839/jabc.2023.030

Yu-Jung Lee

Papers

UV-sensing organic phototransistor memory devices with a doped organic polymer electret composed of triphenylamine-based aggregation-induced emission luminogens

Pentafluorosulfanylated polymers as electrets in nonvolatile organic field-effect transistor memory devices

Anti-inflammatory effects of Lycoris chejuensis callus using biorenovation

Anti-inflammatory effects of biorenovated Torreya nucifera extract in RAW264.7 cells induced by Cutibacterium acnes