Jea Woong Jo

Oligothiophene-terminated poly(ethylene glycol) was synthesized and used as a non-ionic and amphiphilic surfactant for fabricating high-quality single-walled carbon nanotube (SWCNT) films by a simple spin coating method. The absence of charge repulsion between SWCNT/surfactant complexes successfully leads to formation of a dense network of SWCNTs on the substrate through a single deposition of spin coating. When the SWCNT film was treated with nitric acid and thionyl chloride after washed with d

The optimization of the number of fluorine substitution in D–A polymers composed of difluorobithiophene and benzothiadiazole reveals that the polymer with mono-fluorinated benzothiadiazole exhibits a PCE of 9.14%.

For the purpose of examining the tuning of photophysical property by fluorine atom substitution, fluorinated and nonfluorinated poly(3,4-dialkylterthiophenes) (PDATs) were synthesized, and their photovoltaic properties were compared. Fluorinated PDATs exhibit a deeper highest occupied molecular orbital energy level than nonfluorinated ones, leading to higher open-circuit voltage in organic solar cells and also enhanced molecular ordering as evidenced by a vibronic shoulder in UV–vis spectra, π–π

For the purpose of investigating the effect of fluorination position on D−A type conjugated polymer on photophysical and photovoltaic properties, two types of fluorinated polymere are synthesized, HF with fluorination on electron‐donating unit and FH with fluorination on electron‐accepting unit. Compared to non‐fluorinated polymer, fluorinated polymers exhibit deeper HOMO energy levels without change of bandgap and stronger vibronic shoulder in UV−visible absorption, indicating that fluorination

Colloidal quantum dots (CQDs) are promising solution-processed infrared-absorbing materials for optoelectronics. In these applications, it is crucial to replace the electrically insulating ligands used in synthesis to form strongly coupled quantum dot solids. Recently, solution-phase ligand-exchange strategies have been reported that minimize the density of defects and the polydispersity of CQDs; however, we find herein that the new ligands exhibit insufficient chemical reactivity to remove orig

The energy disorder that arises from colloidal quantum dot (CQD) polydispersity limits the open-circuit voltage (V_OC ) and efficiency of CQD photovoltaics. This energy broadening is significantly deteriorated today during CQD ligand exchange and film assembly. Here, a new solution-phase ligand exchange that, via judicious incorporation of reactivity-engineered additives, provides improved monodispersity in final CQD films is reported. It has been found that increasing the concentratio

All‐polymer solar cells (all‐PSCs) utilizing p ‐type polymers as electron‐donors and n ‐typepolymers as electron‐acceptors have attracted a great deal of attention, and their efficiencies have been improved considerably. Here, five polymer donors with different molecular orientations are synthesized by random copolymerization of 5‐fluoro‐2,1,3‐benzothiadiazole with different relative amounts of 2,2′‐bithiophene (2T) and dithieno[3,2‐ b ;2′,3′‐ d ]thiophene (DTT). Solar cells are prepared by blen

A series of anionic self‐doped conjugated polyelectrolytes (CPEs) by copolymerization of a 1,4‐bis(4‐sulfonatobutoxy)benzene moiety with different counter monomers of thiophene, bithiophene, and terthiophene is reported. The CPEs show high conductivity of ≈10 −4 S cm −1 due to being self‐doped in a neutral state and exhibit excellent hole transporting property in the out‐of‐plane direction, compared with poly(3,4‐ethylenedioxythiophene):poly(styrene‐sulfonate) (PEDOT:PSS). Moreover, the CPE inco

A new graft-type polymer which exhibits dual functionality of efficient charge transport and interfacial passivation was synthesized as a dopant-free hole transport material for indoor perovskite photovoltaics.

Abstract As ‘flexibility’ has emerged as an important issue in next‐generation electronics, many efforts to find new classes of materials have been devoted to realizing stretchable, bendable and foldable electronic devices. For these devices to be realized, graphene has been considered as one of the most promising candidates for flexible electrodes due to its extraordinary electrical, optical and mechanical properties. Particularly, recent developments in the fabrication and modification of grap

The near-infrared (NIR) sensor technology is crucial for various applications such as autonomous driving and biometric tracking. Silicon photodetectors (SiPDs) are widely used in NIR applications; however, their scalability is limited by their crystalline properties. Organic photodetectors (OPDs) have attracted attention for NIR applications owing to their scalability, low-temperature processing, and notably low dark current density (J_D), which is similar to that of SiPDs. However, th

In electrolyte‐gated organic electronics, including electrochromic devices, organic field‐effect transistors, and organic electrochemical transistors, the underlying working principle is determined by the permeability of the electrochemically active ions within the electrolyte dielectric into the organic semiconductor layer; as such, the carrier mobility of organic semiconductors in electrolyte‐gated devices remains unclear because of the different degrees of ion penetration depending on the fab

Perovskite has emerged as a promising semiconductor for flexible electronics. However, perovskite-based flexible field-effect transistors (FETs) have typically exhibited a low performance owing to their use of conventional polymer dielectrics. To address this, interfacial and compositional engineering has been employed in emerging perovskite transistors to boost their charge-carrier transport. Here, we introduce the interfacial engineering of a perovskite surface using solution-processed poly(3-