Progress on the optoelectronic functional organic crystals

Abstract

Organic crystals constructed by pi-conjugated molecules have been paid great attention to in the field of organic optoelectronic materials. The superiorities of these organic crystal materials, such as high thermal stability, highly ordered structure, and high carrier mobility over the amorphous thin film materials, make them attractive candidates for optoelectronic devices. Single crystal with definite structure provides a model to investigate the basic interactions between the molecules (supramolecular interaction), and the relationship between molecular stacking modes and optoelectronic performance (luminescence and carrier mobility). Through modulating molecular arrangement in organic crystal, the luminescence efficiency of organic crystal has exceeded 80% and carrier mobility has been up to the level of 10 cm 2 ·V −1 ·s −1 . Amplified stimulated emission phenomena have been observed in many crystals. In this paper, we will emphatically introduce the progress in optoelectronic functional organic crystals and some correlative principle.organic crystals, luminescence, mobility, laser, field effect In the past twenty years, great progress has been made in the field of organic optoelectronic functional materials, such as light-emitting diodes (LEDs) [1 -3] , optically pumped lasers [4,5] , and field-effect transistors (FETs) [6][7][8] . Amorphous semiconductor materials have been extensively investigated because of their operational convenience, since the first high efficiency organic light-emitting diode (OLED) [9] was fabricated by Tang et al. using the vacuum deposition method, and the first organic field-effect transistor (OFET) [10] was fabricated by Tsumura et al. using polythiophene thin film. However, many defects (impurity and structural defects) existing in amorphous materials lead to very low carrier mobility, and then sharply influence the performance of organic semiconductor devices. On the contrary, organic crystals usually present higher mobility, attributed to the very low content of impurity and highly ordered molecule arrangement, as well as highly thermal stability. In recent years, organic single-crystal materials and devices have become a novel investigative hotspot.Scientists have begun to pay attention to the optoelectronic behavior of organic crystals since the 1960s.In the year of 1963, electroluminescence was firstly observed in anthracene single-crystals [11] . In 1974, Avanesjan et al. [12] observed the phenomena of optically pumped laser in anthracene crystals. Later, some organic crystals with high quality and large dimension were successfully obtained, along with the gradually mature technology of growing organic single-crystals; then the crystals were used in testing for some important physical phenomena. For example, the phenomena of amplified spontaneous emission (ASE) were observed in different organic crystals [13][14][15] , which make it possible to realize the electrically pumped laser. Electrically pumped laser requires that the materials must possess high carrier mo-

Synthesis and fluorescent investigations of VBL-based waterborne polyurethane dye

“…It was ascribed to the following two factors: first, VBL was anchored to the polyurethane chains through the reaction of hydroxyl group with NCO-terminated prepolymer, which hindered the formation of exciplex of VBL [15][16][17][18][19] and the intramolecular rotation and vibration of VBL, which could cause a decrease in fluorescence [20]. Secondly, VBL-WPU formed emulsion with electrical double surface layers due to the ionization of acidic groups [21], leading to augmented light absorption area.…”

Progress in long wavelength emission in fluorene-based electroluminescent blue materials

“…The photo-or electrooxidative degradation process leading to low-energy emission bands in disubstituted "hydrogen-free" PF needs to be further studied, which is a very urgent topic especially in order to improve the long-term and color stability of polyarylene-based blue OLEDs. In this regard, the research of long wavelength emission in FEBMs will be a long-term endeavor [66] .…”

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

“…Among them, organic single‐crystalline semiconductors (OSCSs) constructed by π‐conjugated molecules in long‐range periodic order have emerged as a unique optoelectrical material . Their defined structures provide an opportunity to investigate the impact of the basic molecular interactions on the structure–property relationships and reveal fundamental physics in organic semiconductors.…”

“…This enthusiasm for the study of OSCSs has extended the applications range to various high‐performance and low‐cost optoelectronic devices. A series of broad reviews highlighting the most important progress obtained by OSCSs has finished in different aspects including growth strategies, materials design, and device applications . However, none of the reviews so far has focused on the electrical‐pumping light‐emitting behavior, which is not only scientifically important but also technologically imperative for EL devices.…”

“…[22][23][24] Among them, organic single-crystalline semiconductors (OSCSs) constructed by -conjugated molecules in longrange periodic order have emerged as a unique optoelectrical material. [25][26][27][28][29][30][31][32][33][34][35] Their defined structures provide an opportunity to investigate the impact of the basic molecular interactions on the structure-property relationships and reveal fundamental physics in organic semiconductors. Also, the additional features of OSCSs, such as low impurity levels, high carrier mobility, and high thermal stability, make them more attractive in the field of optoelectronics.…”