Generating Long-Lived Triplet Excited States in Narrow Bandgap Conjugated Polymers

Enhanced Long-Term Stability of Perovskite Solar Cells Employing a Benzodithiophene Derivative-Based Dopant-Free Hole Transporting Layer

Perovskite solar cell (PSC) is characterized by high photoelectric conversion efficiency (PCE) and low material cost compared to the silicon solar cell that has already been commercialized. Many researchers are conducting various studies to improve efficiency and stability. To increase power conversion efficiency, hole transporting materials (HTMs) are one of the most important factors for achieving high performance in PSCs. HTMs exhibit an important role in PSCs to transfer the positive charges in between perovskite and counter electrodes. Among the various HTMs, Spiro-OMeTAD has been widely used in PSCs. However, due to its reliance on additives to enhance hole mobility, Spiro-OMeTAD suffers from degradation issues that compromise its long-term stability. So, it is necessary to develop new HTMs to replace Spiro-OMeTAD for their low stability and expensiveness in future application of PSCs. Therefore, we designed and synthesized the materials named PEH-23 and PEH-24 incorporating dialkoxyphenyl and dialkoxybenzodithiophene. As the conjugation length increases, the material demonstrates improved stability, suggesting its potential as an effective HTM with long-term reliability.

Molecular dynamics study on the mitigation of radiation damage caused by electron pulses

The reduction of radiation damage represents a long-term objective for electron microscopists, particularly those engaged in the study of biological and organic matter. Recently, electron pulses in ultrafast transmission electron microscopy have been demonstrated to serve as a damage mitigation technique for radiation-sensitive materials. Nevertheless, the underlying mechanism of the mitigation effects remains unclear. In this study, we investigate the radiation damage of graphene induced by pulsed electrons using molecular dynamics simulations within the framework of binary elastic collisions. For electron irradiation at 200 keV, it was found that the pulsed electron beam corresponds to a larger threshold angle (1.4 rad) than that for a random beam (1.0 rad). This is because two electrons can be prevented from briefly interacting with the same or a neighboring atom by the use of well-controlled electron pulses. While such a mitigation of radiation damage is only apparent near the threshold angle, and there are likely other reduction mechanisms, our results provide insight into the mitigated radiation damage of electron pulses.

Total Synthesis of the Dimeric Phytocannabinoid Cannabitwinol (CBD Dimer) and Its Analogues

A new synthetic route to access the natural product phytocannabinoid cannabitwinol (1) starting from commercially available raw materials is disclosed. We have also demonstrated the synthesis of other related dimers, including their enantiomers, using the present sequence. This route avoids the legal constraints concerning the acquisition of cannabis plant material or CBD.

Appending Coronene Diimide with Carbon Nanohoops Allows for Rapid Intersystem Crossing in Neat Film

The development of innovative triplet materials plays a significant role in various applications. Although effective tuning of triplet formation by intersystem crossing (ISC) has been well established in solution, the modulation of ISC processes in the solid state remains a challenge due to the presence of other exciton decay channels through intermolecular interactions. The cyclic structure of cycloparaphenylenes (CPPs) offers a unique platform to tune the intermolecular packing, which leads to controllable exciton dynamics in the solid state. Herein, by integrating an electron deficient coronene diimide (CDI) unit into the CPP framework, a donor-acceptor type of conjugated macrocycle (CDI-CPP) featuring intramolecular charge-transfer (CT) interaction was designed and synthesized. Effective intermolecular CT interaction resulting from a slipped herringbone packing was confirmed by X-ray crystallography. Transient spectroscopy studies showed that CDI-CPP undergoes ISC in both solution and the film state, with triplet generation time constants of 4.5 ns and 238 ps, respectively. The rapid triplet formation through ISC in the film state can be ascribed to the cooperation between intra- and intermolecular charge-transfer interactions. Our results highlight that intermolecular CT interaction has a pronounced effect on the ISC process in the solid state, and shed light on the use of the characteristic structure of CPPs to manipulate intermolecular CT interactions.