Search

Molecular doping is an extremely useful approach for the optoelectronic properties tuning of organic materials, particularly crystalline luminescent semiconductors. Usually, dopant materials with good luminescence properties are used to improve the optoelectronic properties of host materials. However, the host-dopant compatibility and their selection criteria remain unclear. It is generally considered that the host and dopant should have a "similar" structure, which does not allow one to perform a thorough systematic design and choice of materials for obtaining low-defect doped organic semiconductors. Herein, we report a systematic experimental study coupled with existing literature data on host-dopant compatibility in a series of symmetric linear conjugated small molecules. Molecular planarity, short molecular axis and side polar substituents were demonstrated to be critical for successful host–guest molecular doping. Heterocyclic unit type and arrangement, molecular long axis, conjugation chain length and terminal substituents were demonstrated to not affect the host-dopant compatibility. An elaborated molecular doping guide is highly demanded for the systematic smart design of novel doped high-performance luminescent organic semiconductor materials. [ABSTRACT FROM AUTHOR]

Heteroaryl-containing co-oligomers are considered among the most promising materials for organic optoelectronics. In this work we synthesized a series of linear furan/phenylene co-oligomers (FPs) with different molecular length and studied their structure, luminescence and charge transport properties. The X-ray diffraction experiments revealed the higher distortion of molecular planarity for the longer FPs which is assigned to the crystal environment effect. All FPs demonstrated stability and high photoluminescence quantum yield (PL QY) both in solution and vapor-grown single crystals. The absolute PL QY as high as 70% was demonstrated for FP6 single crystal. The top-contact top-gate organic field-effect transistors (OFETs) demonstrated virtually the same mobility ∼0.35 cm 2 /Vs for a FPs with different conjugation chain. However the threshold voltage for the studied OFETs was demonstrated to be significantly reduced for a co-oligomer FP7 with longer conjugation chain. Thus we conclude that the increase of conjugation chain for co-oligomers does not benefit an increase of charge carrier mobility but improve the crystal/dielectric interface. [ABSTRACT FROM AUTHOR]