Backbone-driven host-dopant miscibility modulates molecular doping in NDI conjugated polymers

Molecular doping is the key to enabling organic electronic devices, however, the design strategies to maximize doping efficiency demands further clarity and comprehension. Previous reports focus on the effect of the side chains, but the role of the backbone is still not well understood. In this study, we synthesize a series of NDI-based copolymers with bithiophene, vinylene, and acetylenic moieties (P1G, P2G, and P3G, respectively), all containing branched triethylene glycol side chains. Using computational and experimental methods, we explore the impact of the conjugated backbone using three key parameters for doping in organic semiconductors: energy levels, microstructure, and miscibility. Our experimental results show that P1G undergoes the most efficient n-type doping owed primarily to its higher dipole moment, and better host–dopant miscibility with N-DMBI. In contrast, P2G and P3G possess more planar backbones than P1G, but the lack of long-range order, and poor host–dopant miscibility limit their doping efficiency. Our data suggest that backbone planarity alone is not enough to maximize the electrical conductivity (σ) of n-type doped organic semiconductors, and that backbone polarity also plays an important role in enhancing σ via host–dopant miscibility. Finally, the thermoelectric properties of doped P1G exhibit a power factor of 0.077 μW m(−1) K(−2), and ultra-low in-plane thermal conductivity of 0.13 W m(−1)K(−1) at 5 mol% of N-DMBI, which is among the lowest thermal conductivity values reported for n-type doped conjugated polymers

Backbone-Driven Host-Dopant Miscibility Modulates Molecular Doping In NDI Conjugated Polymers

Molecular doping is the key to enabling organic electronic devices, however, the design strategies to maximize doping efficiency demands further clarity and comprehension. Previous reports focus on the effect of the side chains, but the role of the backbone is still not well understood. In this study, we synthesize a series of NDI-based copolymers with bithiophene, vinylene, and acetylenic moieties (P1G, P2G, and P3G, respectively), all containing branched triethylene glycol side chains. Using computational and experimental methods, we explore the impact of the conjugated backbone using three key parameters for doping in organic semiconductors: energy levels, microstructure, and miscibility. Our experimental results show that P1G undergoes the most efficient n-type doping owed primarily to its higher dipole moment, and better host–dopant miscibility with N-DMBI. In contrast, P2G and P3G possess more planar backbones than P1G, but the lack of long-range order, and poor host–dopant miscibility limit their doping efficiency. Our data suggest that backbone planarity alone is not enough to maximize the electrical conductivity (σ) of n-type doped organic semiconductors, and that backbone polarity also plays an important role in enhancing σ via host–dopant miscibility. Finally, the thermoelectric properties of doped P1G exhibit a power factor of 0.077 μW m−1 K−2, and ultra-low in-plane thermal conductivity of 0.13 W m−1K−1 at 5 mol% of N-DMBI, which is among the lowest thermal conductivity values reported for n-type doped conjugated polymers

Side-chain engineering of regioregular copolymers for high-performance polymer solar cells processed with nonhalogenated solvents

Conjugated polymers for bulk heterojunction polymer solar cells (BHJ PSCs) should be processed with nonhalogenated solvents because of environmental concerns. Here, we report novel regioregular copolymers for high-performance PSCs processed with nonhalogenated solvents. The regioregular copolymers (i.e., rr-PfBT2f4T-2OD and rr-PfBT2f4T-2DT) consist of 3 '',4 '-difluoro-2,2 ':5 ',2 '':5 '',2"'-quaterthiophene (2f4T) with different side chains (2-octadodecyl (OD) and 2-decyltetradecyl (DT)) and 5-fluorobenzo[c][1,2,5]thiadiazole (fBT). The regioregular copolymers with controlled fBT orientation show high solubility in nonhalogenated solvents. Both regioregular copolymers possess suitable energy levels, leading to sufficient energy offsets with a nonfullerene acceptor, BTP-eC11. An rr-PfBT2f4T-2DT:BTP-eC11-blended film exhibited predominant face-on orientation compared to the rr-PfBT2f4T-2OD:BTP-eC11-blended film. In addition, the rr-PfBT2f4T-2DT:BTP-eC11-blended film showed much more balanced hole/electron mobility (mu(h)/mu(e) similar to 4.73) than rr-PfBT2f4T-2OD:BTP-eC11-blended film (mu(h)/mu(e) similar to 45.86). Therefore, rr-PfBT2f4T-2DT:BTP-eC11-based PSCs, processed with 1,2,4-trimethylbenzene, showed a power conversion efficiency of 13.21% which is 60% higher than rr-PfBT2f4T-2OD:BTP-eC11-based PSCs.FALS

A 0.8-to-2.3GHz Quadrature Error Corrector with Correctable Error Range of 101.6ps Using Minimum Total Delay Tracking and Asynchronous Calibration On-Off Scheme for DRAM Interface

As data transfer rates increase, clock frequencies used for high-speed data paths also increase. Thus, multiphase clocks are typically utilized in DRAMs to relax timing margins because of the reduced timing budget. However, phase errors between multiphase clocks, due to device mismatch, degrade the valid data sampling window. To reduce phase error, several multiphase correction schemes have been proposed [1]-[4]. The active poly-phase filter-based open-loop scheme exhibits a small RMS jitter contribution, but the remaining phase error after the error correction is considerably varied and large in its operating frequency range [1]. A distributed delay-locked loop (DLL) [2] offers the smallest RMS jitter, but the residual phase error is non-negligible as well due to the mismatch of error detection circuits in each calibration loop. The phase error corrector with a relaxation oscillator-based phase detector is also susceptible to the mismatch [3]. The digital DLL-based scheme adopts a shared digital feedback loop to eliminate the effect of mismatch [4]. However, it shows a larger RMS jitter contribution than the distributed DLL due to quantization noise and the increased clock path delay. Since the delay of in-phase clock is always fixed at the mid-point, overall set of codes of digitally-controlled delay lines (DCDLs) may not be at their optimum in terms of jitter. Because jitter and total delay of clock paths are increased more than necessary, it leads to degradation of the data eye. In this paper, an improved quadrature error corrector (QEC), the calibration of which starts from the minimum delay code over all DCDLs, is proposed along with an asynchronous and seamless-calibration on-off scheme for the reduction of power consumption in the operating state after calibration.N

Pd-Catalyzed Regioselective Asymmetric Addition Reaction of Unprotected Pyrimidines to Alkoxyallene

Catalytic asymmetric synthesis of N-heterocyclic glycosides free of protecting and directing groups is reported. The key reaction is highlighted by the atom-efficient and regioselective addition of unprotected pyrimidines to highly functionalized alkoxyallene. Numerous acyclic and cyclic N-heterocyclic glycosides are accessed with minimal formation of organic byproducts. The synthetic utility of the reaction is demonstrated by the first catalytic asymmetric synthesis of anticancer pharmaceutical (-)-Tegafur and stereoselective synthesis of an oxepane nucleoside derivative.1110sciescopu

Oxynitride Amorphous Carbon Layer for Electrically and Thermally Robust Bipolar Resistive Switching

Abstract Advanced resistive random‐access memory (ReRAM) devices based on resistive switching (RS) have been intensely studied for future high‐density nonvolatile memory devices owing to their high scalability, simplified integration, fast operation, and ultralow power consumption. Among the recently considered active media, diverse carbon‐based media have emerged because of numerous benefits of simple chemical composition, desirable speed, and cost‐effective scalability. However, these media are still susceptible to undesirable reliability issues, including poor endurance and retention and uncontrollable operation voltage distribution. In this study, an oxynitride amorphous carbon active medium governed by appropriate nitrogen content during growth is introduced to facilitate high electrical stability, such as a distinct pulse endurance of more than 107 cycles, a high retention time of 105 s at 85 °C, and increased uniformity in the SET/RESET distribution with thermally robust RS stability even at a high annealing temperature of 400 °C. The findings are possibly the result of adapting an sp2–sp3 conversion nature assisted by the presence of pyridinic N or pyrrolic N as a substitution reaction

Factors Limiting the Operational Stability of Tin–Lead Perovskite Solar Cells

Tin–lead perovskite solar cells (TLPSCs) have emerged as one of the most efficient photovoltaic technologies. However, their stability under operational conditions (ambient air, temperature, bias, and illumination) is lagging behind their sharp efficiency increase, restraining their further development. In this Focus Review, we provide insights into the degradation mechanisms of tin–lead perovskites and summarize the principal factors that currently limit the operational stability of TLPSCs. Specifically, perovskite composition and the device architecture stand out as critical aspects governing their sensitivity toward stressors such as temperature and light. We discuss several strategies to overcome these limitations and emphasize the adoption of standardized methods to quantify the lifetime of a device. We further propose using various characterization techniques to identify possible device failure mechanisms. We expect this Focus Review to assist in the progress toward the development of efficient and stable perovskite devices

Straightforward Delivery of Linearized Double-Stranded DNA Encoding sgRNA and Donor DNA for the Generation of Single Nucleotide Variants Based on the CRISPR/Cas9 System

CRISPR/Cas9 for genome editing requires delivery of a guide RNA sequence and donor DNA for targeted homologous recombination. Typically, single-stranded oligodeoxynucleotide, serving as the donor template, and a plasmid encoding guide RNA are delivered as two separate components. However, in the multiplexed generation of single nucleotide variants, this two-component delivery system is limited by difficulty of delivering a matched pair of sgRNA and donor DNA to the target cell. Here, we describe a novel codelivery system called “sgR-DNA” that uses a linearized double-stranded DNA consisting of donor DNA component and a component encoding sgRNA. Our sgR-DNA-based method is simple to implement because it does not require cloning steps. We also report the potential of our delivery system to generate multiplex genomic substitutions in <i>Escherichia coli</i> and human cells

Straightforward Delivery of Linearized Double-Stranded DNA Encoding sgRNA and Donor DNA for the Generation of Single Nucleotide Variants Based on the CRISPR/Cas9 System

CRISPR/Cas9 for genome editing requires delivery of a guide RNA sequence and donor DNA for targeted homologous recombination. Typically, single-stranded oligodeoxynucleotide, serving as the donor template, and a plasmid encoding guide RNA are delivered as two separate components. However, in the multiplexed generation of single nucleotide variants, this two-component delivery system is limited by difficulty of delivering a matched pair of sgRNA and donor DNA to the target cell. Here, we describe a novel codelivery system called “sgR-DNA” that uses a linearized double-stranded DNA consisting of donor DNA component and a component encoding sgRNA. Our sgR-DNA-based method is simple to implement because it does not require cloning steps. We also report the potential of our delivery system to generate multiplex genomic substitutions in <i>Escherichia coli</i> and human cells