Syed Zahid Hassan

A multichannel/multicolor visible light communication (VLC) system using entirely organic components, including organic light emitting diodes (OLEDs) and organic photodiodes (OPDs), is developed to demonstrate indoor lighting applications where the integration of OLEDs and OPDs has significant potential. To achieve this, tricolor (Red/Green/Blue(R/G/B))-selective OPD arrays for the receiver and tricolor OLED arrays for the emitter are developed. For (R/G/B)-selective OPDs, a Fabry-Pérot electrod

Herein, we explore the strategy of realizing a red-selective thin-film organic photodiode (OPD) by synthesizing a new copolymer with a highly selective red-absorption feature. PCZ-Th-DPP, with phenanthrocarbazole (PCZ) and diketopyrrolopyrrole (DPP) as donor and acceptor units, respectively, was strategically designed/synthesized based on a time-dependent density functional theory calculation, which predicted the significant suppression of the band II absorption of PCZ-Th-DPP due to the extremel

Photochromic molecules, which change their molecular structure under external stimuli, are promising for increasing the device functionality without consuming additional space. Azobenzene is a typical chromophore that undergoes cis–trans photoisomerization and thus can control the surface dipole moment when applied as a self-assembled monolayer (SAM). A SAM of fluorinated azobenzene (FAZO) is designed for work function tuning of Au by a large dipole moment difference via photoisomerization. For

A rigid inositol-derived monomer functionalized with azide and alkyne as the complementary reactive groups (CRGs) crystallized as three distinct polymorphs I-III. Despite the unsuitable orientation of CRGs in the crystals for complete polymerization, all the three polymorphs underwent regiospecific and quantitative topochemical azide-alkyne cycloaddition (TAAC) polymerization upon heating to yield three different polymorphs of 1,2,3-triazol-1,4-diyl-linked-poly-neo-inositol. The molecules in the

A molecular and synthetic approach to strengthen the switching performance of diarylethene (DAE)-based organic transistors is proposed. By tuning the length of alkyl side chains of the biphenyl unit attached to 1,2-bis(5-biphenyl-2-methylthien-3-yl)perfluorocyclopentene (DAE), we show that the molecular environment for reversible photoisomerization of DAEs can be optimized. Four different DAEs are synthesized with different alkyl chains (DAE_C0, DAE_C1, DAE_C6, and DAE_C10), and ITIC is chosen t

Recent improvements in the performance of solution-processed semiconductor materials and optoelectronic devices have shifted research interest to the diversification/advancement of their functionality. Embedding a molecular switch capable of transition between two or more metastable isomers by light stimuli is one of the most straightforward and widely accepted methods to potentially realize the multifunctionality of optoelectronic devices. A molecular switch embedded in a semiconductor can effe

were also demonstrated. Furthermore, the OPD demonstrated stable performance during 20 h of continuous operation and minimal performance degradation even after the damp heat test. To fully visualize the advantages of the proposed high-EQE, top-illuminated, semitransparent OPD with spectral asymmetry between absorption and detection, a reflection-type fingerprint platform consisting of 1 OPD-1 oxide field-effect transistor complementary metal-oxide-semiconductor backplane (300 ppi) is designed an

Abstract We propose a highly efficient crosslinking strategy for organic–inorganic hybrid dielectric layers using azide-functionalized acetylacetonate, which covalently connect inorganic particles to polymers, enabling highly efficient inter- and intra-crosslinking of organic and inorganic inclusions, resulting in a dense and defect-free thin-film morphology. From the optimized processing conditions, we obtained an excellent dielectric strength of over 4.0 MV cm −1 , a high dielectric constant o

A fully water-based patterning method for polymer semiconductors was developed and utilized to realize high-precision lateral patterning of various polymers. Water-borne polymer colloids, wherein hydrophobic polymers are dispersed in water with the assistance of surfactant molecules, possess a hydrophilic surface when printed onto a substrate. When this surface is exposed to a washing molecule, the surface of the polymer film recovers its original hydrophobic nature. Such surfactant-induced solu

Photo-responsive nanoscrolls can be successfully fabricated by mixing a polyfluoroalkyl azobenzene derivative and a niobate nanosheet, which is exfoliated from potassium hexaniobate. In this study, we have found that the photo-responsive nanoscroll shows a morphological motion of winding and unwinding, which is basically due to the nanosheet sliding within the nanoscroll, by efficient photo-isomerization reactions of the intercalated azobenzene in addition to the interlayer distance change of th

Abstract When the intensity of the incident light increases, the photocurrents of organic photodiodes (OPDs) exhibit relatively early saturation, due to which OPDs cannot easily detect objects against strong backlights, such as sunlight. In this study, this problem is addressed by introducing a light‐intensity‐dependent transition of the operation mode, such that the operation mode of the OPD autonomously changes to overcome early photocurrent saturation as the incident light intensity passes th

Abstract Over the past decade, molecular‐switch‐embedded memory devices, particularly field‐effect transistors (FETs), have gained significant interest. Molecular switches are integrated to regulate the resistance or current levels in FETs. Despite substantial efforts, realizing large memory window with a long retention time, a critical factor in memory device functionality, remains a challenge. This is due to the inability of an isomeric state of a molecular switch to serve as a stable deep tra

This paper presents a novel hybrid data mining approach for knowledge extraction and classification in medical databases. The approach combines self organizing map, k-means and naive Bayes with a neural network based classifier. The idea is to cluster all data in soft clusters using neural and statistical clustering and fuse them using serial and parallel fusion in conjunction with a neural classifier. The approach has been implemented and tested on a benchmark medical database. The preliminary

We show that crystallographic compatibility, quantum yield, and fatigue resistance are three important factors that diarylethene (DAE) should simultaneously satisfy to realize high-performance photoprogrammable polymer field-effect transistors (FETs). The enhancement of crystallographic compatibility achieved by locating DAE preferentially in the vicinity of intercrystallite tie chains is mainly dependent on the overall molecular volume of DAE. The quantum yield of DAE for photocyclization is de