Naphtho[1,2‑<i>c</i>:5,6‑<i>c</i>′]bis[1,2,5]thiadiazole-Based Nonfullerene Acceptors: Effect of Substituents on the Thiophene Unit on Properties and Photovoltaic Characteristics

The development of new electron-accepting π-conjugated systems for application as nonfullerene acceptors in organic solar cells (OSCs) is urgently needed. Although π-conjugated systems based on naphtho­[1,2-<i>c</i>:5,6-<i>c</i>′]­bis­[1,2,5]­thiadiazole (<b>NTz</b>) and naphthalimide (<b>Np</b>) as central and terminal units, respectively, represent possible candidates for nonfullerene acceptors, our knowledge of the structure–property–device performance relationship of these compounds remains limited. We report herein on an investigation of the effect of the substituents on the thiophene (<b>T</b>) linker between <b>NTz</b> and <b>Np</b> on the properties and photovoltaic performance. The photophysical and physicochemical measurements showed that the absorption behavior as well as frontier-orbital energy levels can be fine-tuned by the choice of the substituent on the thiophene rings. Bulk-heterojunction-type OSCs based on these acceptors under blending with poly­(3-hexylthiophene) as a donor showed various power conversion efficiencies, ranging from 0.26 to 2.14%. The substituents on the thiophene rings also have a significant influence on the blend film properties, which explain the differences in the short-circuit current densities and fill factors in the OSCs. These results indicate the importance of molecular design in preparing nonfullerene acceptors with <b>NTz</b> and <b>Np</b> units in terms of tuning both the molecular properties of the materials and donor–acceptor interface engineering in the blended films

Electronegative Oligothiophenes Based on a Hexafluorocyclopentene-Annelated Thiophene Unit

The synthesis of hexafluorocyclopenta[c]thiophene and its based oligothiophenes is described. The effectiveness of a hexafluorocyclopentene unit to lower the LUMO level without disturbing the effective conjugation could be unambiguously clarified by spectroscopic measurements and X-ray analysis

Synthesis and Spectral Properties of a Highly Soluble Push−Pull Type of Quinoidal Thiophenes

A series of push−pull quinoidal thiophenes 5a,b and 6a−c substituted with an electron-donating 1,3-dithiol-2-ylidene unit and an electron-withdrawing dicyanomethylene unit at the terminals is developed. They are highly soluble in common solvents and deeply colored with extension of the thienoquinoid skeleton

Electronegative Oligothiophenes Based on a Hexafluorocyclopentene-Annelated Thiophene Unit

The synthesis of hexafluorocyclopenta[c]thiophene and its based oligothiophenes is described. The effectiveness of a hexafluorocyclopentene unit to lower the LUMO level without disturbing the effective conjugation could be unambiguously clarified by spectroscopic measurements and X-ray analysis

Novel Selenocycle-Fused TTF-Type of Electron Donors Forming Conducting Molecular Complexes: Bis(ethyleneseleno)tetrathiafulvalene (BES-TTF), Diselenolotetrathiafulvalene (DS-TTF), and Bis(ethyleneseleno)tetraselenafulvalene (BES-TSF)

The title selenocycle-fused tetrathiafulvalene derivatives (BES-TTF and DS-TTF) and tetraselenafulvalene derivative (BES-TSF) have been synthesized as novel electron donors, and their conducting molecular complexes have been studied. Although DS-TTF formed only semiconducting complexes, BES-TTF and BES-TSF gave metallic complexes with various electron acceptors, such as TCNQ, ClO4-, PF6-, and AsF6-. Among them, the TCNQ complex of BES-TSF showed an extraordinarily high room-temperature conductivity of 2700 ± 500 S cm-1, which is of the highest class for a molecular complex. The complexes of BES-TTF underwent a typical metal-to-insulator transition at low temperature, characteristic of one-dimensional organic metals. On the other hand, complexes of BES-TSF were less temperature-dependent and remained highly conducting, even down to cryogenic temperature. The different behaviors of the three donors are discussed on the basis of the crystal structures of their representative complexes as elucidated by X-ray crystallographic analyses

One-Pot Synthesis of Heterocycle-Fused 1,3-Diselenole-2-selones as the Key Precursors of Tetraselenafulvalene-Type Electron Donors

A simple one-pot synthetic method of a series of 4,5-alkylenedichalcogeno-substituted 1,3-diselenole-2-selones by successive treatments of trimethylsilylacetylene with butyllithium, selenium, carbon diselenide, and finally α,ω-bis(chalcogenocyanato)alkanes is described

Synthesis and Properties of the Longest Oligothiophenes: The Icosamer and Heptacosamer

Synthesis and Properties of the Longest Oligothiophenes:  The Icosamer and Heptacosame

Electronegative Oligothiophenes Based on a Hexafluorocyclopentene-Annelated Thiophene Unit

The synthesis of hexafluorocyclopenta[c]thiophene and its based oligothiophenes is described. The effectiveness of a hexafluorocyclopentene unit to lower the LUMO level without disturbing the effective conjugation could be unambiguously clarified by spectroscopic measurements and X-ray analysis

Synthesis of 10-nm Scale Oligothiophene Molecular Wires Bearing Anchor Units at Both Terminal Positions

Oligothiophenes with the length of ca.10 nm bearing anchor units (a protected thiol group or trimethylsilylethynyl) at both terminal positions in the conjugated backbone have been synthesized by the block-coupling synthetic strategy. Their electronic properties were clarified by spectroscopic and electrochemical measurements

Synthesis and Spectral Properties of a Highly Soluble Push−Pull Type of Quinoidal Thiophenes

A series of push−pull quinoidal thiophenes 5a,b and 6a−c substituted with an electron-donating 1,3-dithiol-2-ylidene unit and an electron-withdrawing dicyanomethylene unit at the terminals is developed. They are highly soluble in common solvents and deeply colored with extension of the thienoquinoid skeleton