Advanced Materials

The correlation among molecular conformation, the crystallinity of the morphology, propensity for π–π stacking, J- versus H-aggregation, and photovoltaic performance have been studied based on two newly designed polymers, PBDTTT-S-T and PDT-S-T. The results show that more linear backbone structure is helpful to improve photovoltaic properties of the polymer, and therefore, molecular conformation should be considered for molecular design of photovoltaic polymers.

Supramolecular steric hindrance designs make pyrene-functionalized spiro[fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (Py-SFDBAO) assemble into 2D nanostructures that facilitate aqueous phase large-area synthesis of high-quality and uniform crystalline thin films. Thin-film diodes using aqueous nanosheets as active layers exhibit a non-volatile bistable electrical switching feature with ON/OFF ratios of 6.0 × 10⁴ and photoswitching with conductive gains of 10²–10³. Organic nanosheets are potentially key components for eco-friendly aqueous dispersed organic nano-inks in the application of printed and flexible electronics.

A single nanoplatform integrating laser-induced heat generation by gold nanoparticles and temperature sensing up to 2000 K via (Gd,Yb,Er)₂O₃ nanorods is demonstrated, which presents considerable potential for nanoscale photonics and biomedicine. Blackbody emission is ascertained from the temperature increment with AuNPs concentration, emission color coordinates as a function of the laser pump power, and Planck's law of blackbody radiation.

High performance organic field-effect transistor (OFET)-based ammonia sensors are demonstrated with ultrathin (4–6 molecular layers) dendritic microstripes of an organic semiconductor prepared via dip-coating. These sensors exhibit high sensitivity, fast response/recovery rate, good selectivity, low concentration detection ability, and reliable reversibility, as well as stability. Such a performance represents great progress in the field of OFET-based sensors.

X-ray magnetic circular dichroism (XMCD) measurements and density functional theory (DFT)+U calculations reveal an unexpected antiferromagnetic coupling between physisorbed paramagnetic Co-porphyrin molecules and a Ni surface, separated by a graphene layer. A positive magnetization at the Ni substrate atoms is mediated by graphene and induces a negative one at the Co site, despite only a very small overlap between macrocyclic π and graphene p_z-orbitals.