Crystallization from a Droplet: Single-Crystalline Arrays and Heterojunctions for Organic Electronics

Peng, Boyu; Wu, Ruihan; Li, Hanying

doi:10.1021/acs.accounts.1c00537

Cited by 19 publications

(15 citation statements)

References 47 publications

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“…[ 36,37 ] It should also be noted that the uniqueness of PAA surface, including the existence of strong interactions with molecules and the promotion of ordered packing of molecules, can ensure efficient nucleation and crystallization rates that allow it to match the evaporation rate during the TPCL receding process. [ 38 ] Overall, the self‐formed stable receding TPCL on the PAA surface combined with its efficient induced molecular crystallization enables the successful preparation of sub‐centimeter‐scale, ultrathin and highly aligned single crystals, as characterized below.…”

Section: Resultsmentioning

confidence: 99%

Challenging Bendable Organic Single Crystal and Transistor Arrays with High Mobility and Durability toward Flexible Electronics

Yang

Sun

et al. 2022

Advanced Materials

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materials have intrinsic advantages to meet these requirements, and they can adapt to various complex and extreme flexibility conditions to maintain performance without significant degradation. [7][8][9] However, organic semiconductor films used in flexible electronics are almost polycrystalline or amorphous, which severely limits the availability of high carrier mobility owing to the existence of a large number of grain boundaries, defects, and traps in the film. [9][10][11][12][13] Therefore, organic single crystals are more ideal candidates for flexible electronics, which allow organic materials to approach their ultimate intrinsic properties. [14,15] Moreover, it has been shown that introducing strain in organic single crystals can further enhance the device performance by suppressing molecular vibrations or shortening π-π distances. [16,17] However, the fabrication of large-area organic single crystals on polymer substrates generally used in flexible devices is encountering huge challenges. On the one hand, commonly hydrophobic polymer substrates result in a limited spreading area of the molecular solution, which hinders the large-area assembly of organic crystals. [18,19] Also, due to the generally good solubility of polymers, the prolonged assembly time may cause damage to the underlying polymer substrate. On the other hand, the growth of large-area organic single crystals requires sophisticated assembly strategies. [20][21][22][23] The currently well-developed technologies include solution Bendable organic single crystals are promising candidates for flexible electronics owing to their superior charge-transport properties. However, large-area high-quality organic single crystals are rarely available on the polymer substrates generally used in flexible electronics. Here, a surfaceassisted assembly strategy based on a polymer modification, poly(amic acid) (PAA), is developed to grow large-area organic singe crystals on polymer substrates using a simple drop-casting method. The unique surface properties of PAA that enable molecular solution superwetting and promote molecular ordered assembly produce an extraordinary self-driven "meniscusguided coating" behavior, enabling the fabrication of millimeter-sized, highly aligned organic single crystals for a variety of organic semiconductors. Organic field-effect transistors based on a mode molecule of 2,7-dioctyl[1] benzothieno[3,2-b][1]benzothiophene demonstrate the highest (average) mobility of 18.6 cm 2 V −1 s −1 (15.9 cm 2 V −1 s −1 ), attractively low operating voltage of −3 V, and high flexible durability. The results shed light on the large-area fabrication of organic single crystals on polymer dielectrics toward high-performance and integrated plastic electronics.

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Section: Resultsmentioning

confidence: 99%

Challenging Bendable Organic Single Crystal and Transistor Arrays with High Mobility and Durability toward Flexible Electronics

Yang

Sun

et al. 2022

Advanced Materials

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“…Single crystals of TIPS-pentacene grown from p-xylene using the droplet-pinned crystallization (DPC) method, a facile solution processing approach to prepare well-aligned single crystals of a variety of organic semiconductors, [41][42][43] were first investigated.…”

Section: Resultsmentioning

confidence: 99%

“…Single crystals of TIPS‐pentacene grown from p ‐xylene using the droplet‐pinned crystallization (DPC) method, a facile solution processing approach to prepare well‐aligned single crystals of a variety of organic semiconductors, [ 41–43 ] were first investigated. Divinyltetramethyldisiloxane‐bis(benzocyclobutene) (BCB)‐covered SiO 2 /Si substrates were used to grow the crystals as the BCB layer (10 nm thick) was found to efficiently eliminate the electron traps arising from the surface hydroxyl group on SiO 2 and be beneficial to electron transport.…”

Section: Resultsmentioning

confidence: 99%

Effect of Aromatic Solvents Residuals on Electron Mobility of Organic Single Crystals

Xue

Peng

et al. 2022

Adv Elect Materials

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Ideally, balanced transport for both hole and electron carriers is favored in these double-carrier devices. But in actual, there is still a big lag between the electron and hole transport properties. For instance, the extremely high hole mobility has reached much more than 20 cm 2 V −1 s −1 , [10][11][12][13][14] but in sharp contrast, very few literatures have reported electron mobility beyond 10 cm 2 V −1 s −1 . [15][16][17][18][19] Understanding the determining factors that limit the charge mobility, especially for electron transport, is significant yet challenging. Several typical obstacles to electron conductance, such as the high electron injection barriers [20][21][22] and the electron traps at the semiconductor-dielectric interface, [23] have been widely studied. The polarity of dielectric layer, consisting of a set of dipoles, [24] has another crucial effect. In 2003, Veres et al. observed that charge transport showed strong correlation with dielectric polarizability and they put forward that the dielectric layer could change the density of states by local polarization effects and thus affect the charge transport and indeed, carrier localization is enhanced by insulators with larger permittivity. [22,25] The dominant mechanism is the so-called dipolar disorder. [25][26][27][28] Hulea et al. carried on measurements on rubrene single-crystal devices for the observation of intrinsic charge-transport characteristics and reported that the mobility dependence on dielectric polarizability has a dynamic origin owing to the coupling of the charged carriers in the organic conducting channel to the ionic lattice of the dielectric. [29] This coupled carrier-polarization cloud is referred to as a "Fröhlich polaron" [30][31][32] and moves with electron (or hole). The authors also demonstrated that the charge mobility would switch from a band-like character to a hopping one when the dielectric polarizability increased. In addition to the polarity of dielectrics, we further found that the polarity effects could arise from the solvent residues in solution-processed organic semiconductors. In fact, the existence of polar solvent residues is identified as a factor detrimental to electron transport. [15,33] Both of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene), and an n-type material, 6,13-bis(triisopropyl silylethynyl)-5,7,12,14-tetraazapentacene (TIPS-TAP), have been examined. Crystals of TIPS-pentacene grown from non-polar solvents exhibited ambipolar transport for the first time with Balanced electron and hole transport properties are essential for various organic electrical/optoelectrical applications such as organic solar cells, complementary circuits, and light-emitting transistors. However, the electron transport in organic semiconductor lags far behind the hole side, making it with vital significance to seek the factors that limit the electron mobility. Here, the authors demonstrate that the π-conjugated solvents, as essential components in the widely-used solution processing techniques, can signific...

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“…The droplet-pinned crystallization (DPC) method, which is a modified version of the drop casting technique, uses a small piece of Si wafer as a "pinner" in the center of the droplet to prevent droplet sliding and produce uniform polymer films and aligned crystals arrays of small molecules (Figure 5c). [66,67] The pinner fixes solution droplets containing small molecules and facilitates the steady growth and good alignment of the crystal, reducing the thickness inhomogeneity that occurs when using typical droplets. Huang et al used this technique to grow well-aligned crystals of DPP-di(4-fluorophenyl) (FPDPPPF) and avoided rough crystal surfaces with steps that interfere charge carrier transport.…”

Section: Droplet-pinned Crystallizationmentioning

confidence: 99%

Recent Advances in Realizing Highly Aligned Organic Semiconductors by Solution‐Processing Approaches

Yan

Zhao

et al. 2022

Small Methods

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Solution‐processing approaches are widely used for controlling the aggregation structure of organic semiconductors because they are fast, efficient, and have strong practicability. Effective regulation of the aggregation structure of molecules to achieve highly ordered molecular stacking is key to realizing effective carrier transport and high‐performance devices. Numerous studies have achieved highly aligned organic semiconductors using different solution‐processing approaches. This article provides a detailed review of the prevalent solution‐processing technologies and emerging methods developed over the past few years for the alignment of organic semiconducting materials. These technologies and methods are classified according to the processing principle. This review focuses on the principles of different experimental techniques, improvements upon the conventional methods, and state‐of‐the‐art performance of resulting devices. In addition, a brief discussion of the characteristics and development prospects of various methods is presented.

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Crystallization from a Droplet: Single-Crystalline Arrays and Heterojunctions for Organic Electronics

Cited by 19 publications

References 47 publications

Challenging Bendable Organic Single Crystal and Transistor Arrays with High Mobility and Durability toward Flexible Electronics

Challenging Bendable Organic Single Crystal and Transistor Arrays with High Mobility and Durability toward Flexible Electronics

Effect of Aromatic Solvents Residuals on Electron Mobility of Organic Single Crystals

Recent Advances in Realizing Highly Aligned Organic Semiconductors by Solution‐Processing Approaches

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