Rajib Mondal

Milliken & Company · MHP

Introduction: Silver-containing wound dressings commonly are used when there is a risk of infection. These commercial antimicrobial silver dressings have various compositions that use different substrates and/or silver sources. Common silver sources are ionic silver (Ag+) and metallic silver (Ag0). A third source of silver is ion exchange silver c...

The virtual high-throughput screening framework of the Harvard Clean Energy Project allows for the computational assessment of candidate structures for organic electronic materials – in particular photovoltaics – at an unprecedented scale. We report the most promising compounds that have emerged after studying 2.3 million molecular motifs by means...

The bisdecarbonylation of bridged α-diketones has turned into an important reaction for the photochemical generation of higher acenes, in particular under matrix isolation conditions. Here, a computational mechanistic analysis of the bisdecarbonylation of dibenzobicyclo[2.2.2]octadienedione 2 to anthracene 1 is presented. The study employed the B3L...

Atomic layer deposition (ALD) was used to fabricate Al(2)O(3) recombination barriers in solid-state dye-sensitized solar cells (ss-DSSCs) employing an organic hole transport material (HTM) for the first time. Al(2)O(3) recombination barriers of varying thickness were incorporated into efficient ss-DSSCs utilizing the Z907 dye adsorbed onto a 2 μm-t...

Conjugated polymers with nearly planar backbones have been the most commonly investigated materials for organic-based electronic devices. More twisted polymer backbones have been shown to achieve larger open-circuit voltages in solar cells, though with decreased short-circuit current densities. We systematically impose twists within a family of pol...

Regioregular pentacene-containing polymers were synthesized with alkylated bithiophene (BT) and cyclopentadithiophene (CPDT) as comonomers. Among them, 2,9-conjugated polymersPnBT-2,9 and PnCPDT-2,9 achieved the best performance in transistor and photovoltaic devices respectively. The former achieved the most highly ordered structures in thin films...

We demonstrate that poly(3,4-dialkylterthiophenes) (P34ATs) have comparable transistor mobilities (0.17 cm(2) V(-1) s(-1)) and greater environmental stability (less degradation of on/off ratio) than regioregular poly(3-alkylthiophenes) (P3ATs). Unlike poly(3-hexylthiophene) (P3HT), P34ATs do not show a strong and distinct π-π stacking in X-ray diff...

Supplementary Figures S1-S8, Supplementary Table S1, Supplementary Methods and Supplementary References

For organic semiconductors to find ubiquitous electronics applications, the development of new materials with high mobility and air stability is critical. Despite the versatility of carbon, exploratory chemical synthesis in the vast chemical space can be hindered by synthetic and characterization difficulties. Here we show that in silico screening...

A strategic side-chain engineering approach leads to the two orders of magnitude enhancement of charge carrier mobility in phenanthrene based fused aromatic thienopyrazine polymers. Hole carrier mobility up to 0.012 cm2/Vs can be obtained in thin film transistor devices. Polymers were also utilized to fabricate bulk heterojunction photovoltaic devi...

Recent development of a fused aromatic thieno[3.4-b]pyrazine system and their application in optoelectronic devices are reviewed. Introduction of a fused aromatic unit followed by side chain engineering, dramatically enhanced the charge carrier mobility in thin film transistor devices and mobilities up to 0.2 cm2/Vs were achieved. The optoelectroni...

Research interest in solar energy due to climate and energy security concerns has resulted in many photovoltaic technologies. One such example is the dye-sensitized solar cell (DSSC) which employs a monolayer of ruthenium-organic dye molecules adsorbed onto a TiO2 substrate as the photon absorber. The original DSSC design in which an iodine electro...

Grazing incidence X-ray scattering (GIXS) is used to characterize the morphology of poly(3-hexylthiophene) (P3HT)–phenyl-C61-butyric acid methyl ester (PCBM) thin film bulk heterojunction (BHJ) blends as a function of thermal annealing temperature, from room temperature to 220 °C. A custom-built heating chamber for in situ GIXS studies allows for t...

Thiophene enriched fused-aromatic thieno[3,4-b]pyrazine systems were designed and employed to produce low band gap polymers (Eg = 1.0-1.4 eV) when copolymerized with fluorene and cyclopentadithiophene. The copolymers are mainly investigated for organic thin film transistor and organic photovoltaic applications. Molecular packing in the thin films o...

Five new donor−acceptor copolymers containing the electron acceptor benzothiadiazole (BTZ) linked to the electron donors fluorene (FL) or cyclopentadithiophene (CPDT) via vinylene units were synthesized to study polymer structure−property relationships in organic photovoltaic devices. Both alternating (P) and random copolymers (P1−P4) were prepared...

Removing the adjacent thiophenegroups around the acceptor core in low band gap polymers significantly enhances solar cell efficiency through increasing the optical absorption and raising the ionization potential of the polymer.

The photochemical bisdecarbonylation of bridged alpha-diketones (Strating-Zwanenburg reaction) to give the oligoacenes pentacene (2), hexacene (3), and heptacene (4) is investigated in solid inert gas matrices at cryogenic temperatures. The photodecomposition using visible light irradiation cleanly produces the corresponding oligoacene without form...

Dithiopheric and fluorene co-polymers containing fused aromatic thieno[3,4-b]pyrazine moieties were synthesized for organic thin film transistor (OTFT) and organic photovoltaic (OPV) applications. Suzuki and Stille polycondensation reactions were used for the polymerization. The band gap (E(g)) of the polymers was tuned in the range of 1.15-1.6 eV...

We report the performance of low-bandgap polymers with a new ACTP acceptor in organic transistors (max. field-effect mobility 0.2 cm 2 V À1 s À1), and solar cells (max. efficiency 1.4%). Semiconductive polymers may offer a route to photovoltaic and electronic function when characteristics such as light weight, flexi-bility, and low-temperature proc...

The possible formation of pentacene from a tosylhydrazone of 6,13-dihydro-6,13-ethenopentacene under the conditions of the Shapiro reaction is explored, as previous work demonstrated that the tosylhydrazone of barrelene (bicyclo[2.2.2]octatriene) yields benzene under these conditions [C. Weitemeyer, T. Preuss, and A. de Meijere, Chem. Ber., 1985, 1...

Substituted pentacenes (8a, 8b, 14a, and 14b) were prepared by Strating-Zwanenburg photodecarbonylation of diones (7a, 7b, 13a, and 13b). The compounds are red and stable in the solid state under inert atmosphere as well as in degassed solutions, but not in air. Each is soluble in common organic solvents where, unless protected, they are oxygen sen...

Photophysical and electrochemical properties of 7,16-dihydroheptacenes (1–3) were investigated in detail. Although their HOMO–LUMO gaps are higher than 3 eV, the organic light-emitting diodes containing 1 as the emitting dopant showed green electroluminescence (λmax∼515 and 550nm) even at a concentration of the dopant as low as 1%. The green electr...

Poly(acene)s are significant compounds for various electronic applications. A clean, one-step synthesis involves alpha-diketones (2-4), which undergo facile Strating-Zwanenburg photodecarbonylation producing the corresponding poly(acene)s (i.e., anthracene, hexacene, and heptacene, respectively). Compounds 2-4 show weak fluorescence (lambdaF=approx...

Heptacene, generated in inert gas matrices by photobisdecarbonylation of a bridged alpha-diketone precursor, undergoes ionization into radical anion and radical cation upon UV irradiation.

Heptacene generated in-situ in a polymer matrix using a photochemical route undergoes oxidation with diffused oxygen leading to the formation of endoperoxides. We have found the high reactivity of heptacene, a linear poly(acene), toward molecular oxygen can be used to determine oxygen permeability of polymer films. The rate of disappearance of hept...

Polyacenes, linear poly(benzenoid) hydrocarbons, are significant compounds for various electronic applications. Smaller lower molecular weight members of the series (anthracene, tetracene, and pentacene) have been extensively investigated for their use as semiconductors, as active layers in organic field-effect transistors (OFETs) and in organic li...

A comparative study of suitably functionalized, highly soluble tetraceno[2,3-b]thiophenes (1-3) and pentacenes (4-6) that show higher photoxidative stability than that of unfunctionalized corresponding acenes is reported. The absorption and emission of 1-3 (Amax = 624-656 nm, lambda max = 634-672 nm, PhiF approximately 10%) and 4-6 (Amax = 672-704...

A new class of highly fluorescent and stable carbazole-based dendrimers (1-5) that contain the ethynylbenzene and diethynylbenzene cores has been synthesized and characterized. They show very high extinction coefficients of absorption (A(max) approximately 328-353 nm) and high quantum yields of fluorescence (lambda(max) approximately 386-437 nm; Ph...

The Strating-Zwanenberg photodecarbonylation was used to prepare hexacene (1). Compound 1 was found to be extremely unstable in solution, undergoing dimerization and oxidation. However, when generated in a polymer matrix, 1 survived for more than 12 h under ambient conditions. Hexacenes substituted at the 6 and 15 positions with the phenyl, p-tert-...

Heptacene (1) was generated by the photodecarbonylation of 7,16-dihydro-7,16-ethanoheptacene-19,20-dione (2) in a polymer matrix using a UV-LED lamp (395 +/- 25 nm). Compound 1 showed a long wavelength absorption band extending from 600 to 825 nm (lambdamax approximately 760 nm) and was found to be stable up to 4 h in the polymer matrix. However, i...

Polycyclic aromatic hydrocarbons are important compounds for electronic applications. 7,16-Dihydroheptacene derivatives (1 – 3) and anthanthrene (4) and derivatives (5 – 9) were synthesized and their emission properties compared in solution (λmax = 426 – 467 nm, φF = 0.15 – 0.56, τF = 2.35 – 4.21 ns) and in the solid state (λmax = 420 – 468 nm, φF...

7,16-Dihydroheptacenes (1-3) substituted at the 6, 8, 15, and 17 positions are synthesized as blue emitters potentially useful in organic light emitting diodes (OLEDs). The photophysical properties of 1-3 (lambda(max) = 424-428 nm, phi(F) = 0.15-0.21, tau(F) = 2.35-2.67 ns in CH2Cl2) are discussed. They are shown to be stable and efficient blue emi...

Exciton harvesting is of fundamental importance for the efficient operation of organic photovoltaic devices. The quantum efficiencies of many organic and hybrid organic- inorganic devices are still limited by low exciton harvesting efficiencies. This problem is most apparent in planar heterostructures that suffer from a direct tradeoff between ligh...