Microspacing In-Air Sublimation Growth of Ultrathin Organic Single Crystals

Abstract

Organic single crystals play indispensable roles in high-performance electronic devices because of their completely eliminated or minimized impurities and disorder, wherein ultrathin thickness is a critical prerequisite because charge accumulation in devices occurs within a few molecular monolayers of the semiconductors. The growth of organic crystals through vapor dispels concerns about solubilities and the inclusion of solvents in the final crystals, but achieving an ultrathin thickness for common organic semiconductors is beyond its power. On the basis of our recently invented microspacing in-air sublimation (MAS), the distance between the source and growth position is set to approximate the mean free path of the vaporized molecules. Such a configuration generates a genetic relationship between the morphology of the source materials and that of the grown crystals. By refining the deposition of the source materials using ultrasonic spray, we can obtain ultrathin single crystals with a uniform distribution. We exemplify the strategy through MAS growth of ultrathin DNTT and pentacene single crystals down to five and three molecular monolayers, respectively. Field effect transistors fabricated on the ultrathin crystals exhibited average charge carrier mobilities of 6.08 cm 2 V −1 s −1 for DNTT and 2.39 cm 2 V −1 s −1 for pentacene, and low threshold voltages (∼83% of the devices within 5 V).

Vapor Transport Deposition of Highly Efficient Sb2(S,Se)3 Solar Cells via Controllable Orientation Growth

“…Among them, the vapor speed was crucial for the nucleation density and determined the quality and preferred orientation of the Sb 2 (S,Se) 3 film. Here, we discussed the vapor speed from the perspective of the mean free path (): [ 31 ] where K is the Boltzmann constant; T is the temperature; d is the molecular diameter; and P is the pressure. For simplification, we regarded the vapor molecules as one type and ignored the influence of the remaining air.…”

2D Metal‐Organic Complex Luminescent Crystals

“…[25] The solid-vapor synthesis of 2D Ge-TCNQ crystals is schematically illustrated in Figure 1a, which is recently proposed by Tao's group, namely the microspacing in-air sublimation. [25][26][27] Briefly, two substrates separated by a tiny micrometer-confined spacer were placed on a hot plate, the bottom substrate is adopted as the source substrate to load previously coated Ge-TCNQ thin film, while the top substrate is served as the target substrate to harvest the 2D Ge-TCNQ crystals. In a typical growth procedure, the hot plate was gradually heated up to 150 °C to sublime the Ge-TCNQ thin film and allow it to homogeneously nucleate and crystalize into 2D Ge-TCNQ crystals within one minute on the underlying surface of the target substrate.…”

“…In a typical growth procedure, the hot plate was gradually heated up to 150 °C to sublime the Ge-TCNQ thin film and allow it to homogeneously nucleate and crystalize into 2D Ge-TCNQ crystals within one minute on the underlying surface of the target substrate. The microspacing distance between the two substrates is set to be 300 µm, comparable to the mean free path of the vapor molecules, [25][26][27] where the crystals can be easily crystallized from vapor molecules.…”

“…This approach has recently shown a great promise as a simple yet robust technique for 2D organic crystals growth. [25][26][27] The strong charge-transfer interactions between Ge ion and TCNQ molecules ensure decent PL behavior in the 2D Ge-TCNQ crystals.…”

Organic Semiconductor Micro/Nanocrystals for Laser Applications

“…The evaporated material condenses in droplets on the upper substrate, from which crystals grow. They obtained high quality crystals of anthracene, perylene, pentacene, pyrene among others with sizes from 10 to 50 µm [ 87 , 88 ].…”