Organic Single‐Crystalline Semiconductors for Light‐Emitting Applications: Recent Advances and Developments

Abstract

Organic single‐crystalline semiconductors (OSCSs), as a vital branch of organic semiconductors, have recently attracted intense interest due to their numerous advantages such as highly ordered structure, high carrier mobility, high thermal stability, and low impurity levels, and they have worldwide use in different kinds of applications. In particular, the nature of better luminescence properties and remarkable charge‐transport characteristics is a prerequisite for light‐emitting aspects. Here, a concise overview of the recent progress on OSCSs research is provided, highlighting the prominent properties of OSCSs which are pertinent to light‐emitting behavior. Various crystal‐growth strategies are surveyed for the preparation of high‐quality OSCSs via solution, melting, and vapor phases. Two typical electrical‐pumping light‐emitting devices, including organic light‐emitting transistors and organic light‐emitting diodes, are summarized with recent advances and developments exhibiting the latent potentialities of OSCSs in optoelectronics.

Enhanced Energy Transfer in Doped Bifluorene Single Crystals: Prospects for Organic Lasers

“…Considering this effect, demonstration of low ASE threshold in most single crystals is probably limited by nonoptimal crystal thickness and size ratio for thin stripe excitation measurements. Nevertheless, ASE threshold recorded for doped bifluorene crystals is among the lowest reported for organic crystalline materials . Although ASE threshold in doped crystals are still below best performing amorphous blend films, population inversion can be achieved at significantly lower doping concentrations owing to enhanced energy transfer in well‐ordered crystalline materials.…”

“…Nevertheless, ASE threshold recorded for doped bifluorene crystals is among the lowest reported for organic crystalline materials. [12,14] Although ASE threshold in doped crystals are still below best performing amorphous blend films, [66,67] population inversion can be achieved at significantly lower doping concentrations owing to enhanced energy transfer in well-ordered crystalline materials.…”

“…Herein, strategies have been developed to reduce threshold by applying intricate resonator structures and optimizing amplified spontaneous emission (ASE) properties in solid state gain material . Organic single crystals (SCs) offer multiple advantages to be employed as a gain medium in electrically driven OSLs . Long‐range molecular order in organic SCs ensures enhanced ambipolar carrier transport .…”

2,3-Thienoimide-ended oligothiophenes as ambipolar semiconductors for multifunctional single-layer light-emitting transistors

“…81,82 Extensive reviews can be found elsewhere. 83,84 Unfortunately, obtaining high electroluminescence yields from this class of highly efficient ambipolar materials still requires a great effort. If, on one side, the charge carrier mobility is favored by increasing the intermolecular overlapping as typically occurs in highlyordered crystals, on the other side, the electroluminescence efficiency is significantly reduced upon aggregation.…”

Well‐Balanced Ambipolar Organic Single Crystals toward Highly Efficient Light‐Emitting Devices

“…Organic single crystals with highly ordered structures as well as minimal defects endow them with much higher carrier mobility than the organic amorphous films. [1][2][3][4][5][6][7] The highest recorded mobility approaching 43 cm 2 V −1 s −1 was obtained from a rubrene single crystalbased transistor, which is much higher than that of the amorphous silicon. [8][9][10][11] Therefore, organic single crystals have attracted increasing interest in the area of optoelectronic devices, such as organic light-emitting transistors, [1] organic fieldeffect transistors (OFETs), [2][3] optically pumped lasers, [5] and organic light-emitting devices (OLEDs).…”