Enabling Ultrafast Intramolecular Singlet Fission in Perylene Diimide Tetramer with Saddle-Shaped Linker.

Intramolecular singlet fission (SF) in multichromophore systems is of high interest for photovoltaic application. As an attractive candidate for SF-based devices, enabling efficient SF in covalent oligomers of perylene diimide (PDI) still remains challenging. In this work, inter-PDI SF with τ = ∼150 ps and ∼150% triplet yield in a covalent tetramer COTh-FPDI was facilitated by employing a saddle-shaped cyclooctatetrathiophene (COTh) core and fused linking with PDIs.

The power of clans: How social capital sheltered firms during the COVID-19 pandemic.

Data from 3,555 Chinese listed firms show that firms in cities with greater clan strength faced smaller losses and swifter recovery following COVID-19. Clans were significantly related to individual values facilitating pandemic prevention; these ties guaranteed economic activities and sheltered firms from the shock. Our results frame social capital as a complementarity to formal institutions during crises.

Photovoltaic Performances of Fused Ring Acceptors with Isomerized Ladder-Type Dipyran Cores.

We precisely design and synthesize two A-π-D-π-A type dipyran-cored nonfullerene acceptors (NFAs) and with oxygen atoms at the outer and inner positions, respectively. 3-Hexyloxythiophene is used as the π-spacer to expand the effective conjugation length of the acceptors. These two NFAs possess similar optical band gaps and energy levels.

Facile Synthesis of the O-Functionalized Ladder-Type Dipyran Building Block and Its Application in Polymer Solar Cells.

A new centrosymmetrical dipyran unit (DTDP) is successfully prepared by means of an efficient and universal way, and a series of PDTDP polymers have been prepared so as to assess their potential application in organic photovoltaic. The function of pyran moiety is not merely limited to tune the electron-donating roles and energy levels but it also contributes to solubility improvement. Interestingly, all pyran-based polymers displayed wide absorption ranging from 350 to 780 nm, but varied aggregation phenomena are observed.