In layered COFs, slipping results in non-monotonous variation in CO2adsorption and higher uptakes were found near a slipping distance of 10 Å.

Naphthalene diimide−bithiophene P(NDI2OD-T2) is a well-known donor−acceptor polymer, previously explored as n-type material in all-polymer solar cells (all-PSCs) and organic field effect transistor (OFETs) applications. The optical, bulk, electrochemical, and semiconducting properties of P(NDI2OD-T2) polymer were tuned via random incorporation of perylene diimide (PDI) as coacceptor with naphthalene diimide (NDI). Three random copolymers containing 2,2′-bithiophene as donor unit and varying compositions of naphthalene diimide (NDI) and perylene diimide (xPDI, x = 15, 30, and 50 mol % of PDI) as two mixed acceptors were synthesized by Stille coupling copolymerization. Proton NMR spectra recorded in CDCl 3 showed that the π−π stacking induced aggregation among the naphthalene units could be successfully disrupted by the random incorporation of bulky PDI units. The newly synthesized random copolymers were investigated as electron acceptors in BHJ all-PSCs, and their performance was compared with P(NDI2OD-T2) as reference polymer. An enhanced PCE of 5.03% was observed for BHJ all-PSCs (all-polymer solar cells) fabricated using NDI-Th-PDI30 as acceptor and PTB7-Th as donor, while the reference polymer blend with the same donor polymer exhibited PCE of 2.97% efficiency under similar conditions. SCLC bulk carrier mobility measured for blend devices showed improved charge mobility compared to reference polymer, with PTB7-Th:NDI-Th-PDI30 blend device exhibiting the high hole and electron mobility of 4.2 × 10 −4 and 1.5 × 10 −4 cm 2 /(V s), respectively. This work demonstrates the importance of molecular design via random copolymer strategy to control the bulk crystallinity, compatibility, blend morphology, and solar cell performance of n-type copolymers.

Hydrophobic and surfactant-free ZnO nanoparticles and ZnO decorated graphene nanocomposite (Z@G) with narrow and uniform size distribution were synthesized by a time-efficient microwave-assisted hydrothermal reaction that can be used specifically for application in hybrid photovoltaics. The synthesized ZnO nanoparticles and Z@G nanocomposite showed stable and clear dispersion in chloroform and methanol (with volume ratio of 9 : 1) and chloroform and ethanol (volume ratio 9 : 1).Being hydrophobic, these inorganic samples blend very well with organic polymer solution in chlorobenzene, which is a prerequisite to cast smooth and undisrupted film for hybrid solar cell application. The introduction of these hydrophobic nanoparticles into PCPDTBT:PCBM-based bulkheterojunction polymer solar cells resulted in significant improvement in solar cell J-V characteristics with enhancement in open circuit voltage (V OC ), short circuit current density (J SC ) and thereby overall improvement in cell efficiency. With the optimization of the weight ratio of polymer, fullerene and synthesized ZnO nanoparticles/Z@G nanocomposite, the power conversion efficiencies 1.76% and 3.65% were achieved.

We consider the design of an optimal superlattice thermoelectric generator via the energy bandpass filter approach. Various configurations of superlattice structures are explored to obtain a bandpass transmission spectrum that approaches the ideal "boxcar" form, which is now well known to manifest the largest efficiency at a given output power. Using the non-equilibrium Green's function formalism coupled self-consistently with the Poisson's equation, we identify such an ideal structure and also demonstrate that it is almost immune to the deleterious effect of self-consistent charging and device variability. Analyzing various superlattice designs, we conclude that superlattices with a Gaussian distribution of the barrier thickness offers the best thermoelectric efficiency at maximum power. It is observed that the best operating regime of this device design provides a maximum power in the range of 0.32-0.46 M W/m 2 at efficiencies between 54%-43% of Carnot efficiency. We also analyze our device designs with the conventional figure of merit approach to counter support the results so obtained. We note a high zT el = 6 value in the case of Gaussian distribution of the barrier thickness. With the existing advanced thin-film growth technology, the suggested superlattice structures can be achieved, and such optimized thermoelectric performances can be realized.

No abstract

In this article, we have designed and synthesized a porphyrin with the following molecular architecture A-π-D-π-A in which ethyl rhodanine end capping groups were linked to the core porphyrin donor via an octyl thiophene-ethynylene π bridge denoted as VC117 and used it as an electron donor along with ([6,6] The higher value of J sc is explained by the increased absorption profile of the blend, the higher incident photon to current efficiency (IPCE) response and the better crystallinity of the active layer when processed with solvent additives and thermal annealing while the enhancement of FF is due to the better charge transport capability and the charge collection efficiency of the latter device.

Triazine‐based imine and β‐ketoenamine linked covalent organic frameworks (COFs), TAT‐DHBD (1) and TAT‐TFP (2), have been synthesized from 1,3,5‐tris‐(4′‐aminophenyl)triazine (TAT) and 2,5‐dihydroxybenzene‐1,4‐dicarboxaldehyde (DHBD) or 1,3,5‐triformylphloroglucinol (TFP) under solvothermal conditions in dioxane/mesitylene mixture. These COFs exhibit significant surface areas owing to their meso‐ and micropores. The presence of basic nitrogen sites offers excellent affinity towards Pd nanoparticles and carbon dioxide. Post treatment of COFs 1 and 2 with palladium acetate gives PdII/TAT‐DHBD (3) and PdII/TAT‐TFP (4), which on reduction by NaBH4 yields Pd0/TAT‐DHBD (5) and Pd0/TAT‐TFP (6), respectively. The new COFs have been characterized by FTIR, solid‐state 13C NMR spectroscopy, X‐ray photoelectron spectroscopy (XPS), SEM, TEM, and Brunauer–Emmett–Teller (BET) surface area measurements. TEM studies corroborated the uniform distribution of PdII and Pd0 sites in the COFs. Compounds 3–6 are active towards the Suzuki–Miyaura cross‐coupling of arenes with meager catalyst leaching even after five cycles. In addition, 4 exhibits CO2 uptake of 11 wt % and 7.5 wt % at 273 and 298 K, respectively, at 1 bar.

No abstract