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In the title compound, C9H8O2, an intra­molecular O—H⋯O hydrogen bond generates an S(6) ring. The dihedral angle between the mean plane of the S(6) ring and the benzene ring is 1.89 (2)°. In the crystal, inversion-related mol­ecules are linked by pairs of O—H⋯O hydrogen bonds, forming a cyclic dimers with R 2 2(12) graph-set motif. Weak inter­molecular C—H⋯Ocarbon­yl and C—H⋯Ohy­droxy hydrogen bonds link the dimers into chains along [010], generating two C(6) motifs that overlap three C atoms, forming R 2 2(8) ring motifs.

In this paper, two D-π-D type compounds, C1 and C2, containing dihydrodinaphthopentacene (DHDNP) as a πbridge, p-methoxydiphenylamine and p-methoxytriphenylamine groups as the donor groups were synthesized. The four 4-hexylphenyl groups at the sp 3 -carbon bridges of DHDNP were acquainted with control morphology and improving solubility. The light absorption, energy level, thermal properties, and application as hole-transporting materials in perovskite solar cells of these compounds were fully investigated. The HOMO/LUMO levels and energy gaps of these DHDNP-based molecules are suitable for use as hole-transporting materials in PSCs. The best power conversion efficiencies of the PVSCs based on the C1 and C2 are 15.96% and 12.86%, respectively. The performance of C1 is comparable to that of the reference compound spiro-OMeTAD (16.38%). Compared with spiro-OMeTAD, the C1-based PVSC device showed good stability, which was slightly decreased to 98.68% of its initial efficiency after 48 h and retained 81% of its original PCE after 334 h without encapsulation. These results reveal the potential usefulness of the DHDNP building block for further development of economical and highly efficient HTMs for PVSCs.

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Spider silk is a promising material with great potential in biomedical applications due to its incredible mechanical properties and resistance to bacterial degradation, particularly commercially available strains. However, little is known about the bacterial communities that may inhabit spider webs and how these microorganisms interact with spider silk. In this study, we exposed two exopolysaccharide-secreting bacteria, isolated from webs of an orb spider, to major ampullate (MA) silk from host spiders. The naturally occurring lipid and glycoprotein surface layers of MA silk were experimentally removed to further probe the interaction between bacteria and silk. Extensibility of major ampullate silk produced by Triconephila clavata that was exposed to either Microbacterium sp. or Novosphigobium sp. was significantly higher than that of silk that was not exposed to bacteria. This strain-enhancing effect was not observed when the lipid and glycoprotein surface layers of MA silks were removed. The presence of exopolysaccharides was detected through NMR from MA silks exposed to these two bacteria but not from those without exposure. Here we report for the first time that exopolysaccharide-secreting bacteria inhabiting spider webs can enhance extensibility of host MA silks and silk surface layers play a vital role in mediating such effects.