Crystal Engineering of Dual Channel p/n Organic Semiconductors by Complementary Hydrogen Bonding

Abstract

The supramolecular arrangement of organic semiconductors in the solid state is as critical for their device properties as the molecular structure, but is much more difficult to control. To enable supramolecular design of semiconducting materials, we introduced dipyrrolopyridine as a new donor semiconductor capable of complementary hydogen bonding with naphthalenediimide acceptors. Through a combination of solution, crystallographic, and device studies, we show that the self-assembly driven by H bonding a) modulates the charge-transfer interactions between the donor and acceptor, b) allows for precise control over the solid-state packing, and c) leads to a combination of the charge-transport properties of the individual components. The predictive power of this approach was demonstrated in the synthesis of three new coassembled materials which show both hole and electron transport in single-crystal field-effect transistors. These studies provide a foundation for advanced solid-state engineering in organic electronics, capitalizing on the complementary H bonding.

Rational Design of Charge-Transfer Interactions in Halogen-Bonded Co-crystals toward Versatile Solid-State Optoelectronics

“…[25][26][27] This is partially because of many remained challenges in this direction, and one of them is achieving effective co-crystallization. 28 As reported, there exist many strategies for co-crystal formation, including solution, 29 vapor phase 30 and mechanochemical techniques. 15 Among these methods, solution-based approach is particularly important and commonly used, because it is regarded as the simplest way to obtain organic co-crystal with uniform and regular morphology, which is convenient for further optoelectronic characterizations.…”

Cocrystals Strategy towards Materials for Near‐Infrared Photothermal Conversion and Imaging

“…Organic cocrystal, wherein donors (D) and acceptors (A) self-assemble together with ac rystalline structure through non-covalent interactions, [14] not only has simple preparation methods such as solution, [15] vapor phase, [16] mechanochemical method, [17] but also could demonstrate novel photophysical properties, [18] such as white-light emitting, [19] roomtemperature phosphorescent [20] and nonlinear optical materials, [21] which are rare among organics.Inspecial, the electron delocalization from the donor to the acceptor in chargetransfer (CT) cocrystals contributes more to the appealing physicochemical properties as well as the band engineering for the orbital hybridization. [22] Through effective control of the CT natures,s uch as the degree of charge transfer 1, ground state and excited state dynamics,c harge generation, separation, recombination processes,i tis possible to achieve rational designed functional cocrystals.…”

Organic Cocrystals: Beyond Electrical Conductivities and Field‐Effect Transistors (FETs)

“…There are three main strategies for preparing organic cocrystals,i ncluding vapor-phase (Figure 2a), [36] liquid-phase ( Figure 2b) [25] and solid-phase (mechanochemical, grinding the mixture of donor and acceptor) methods. [31] Thesolutionbased technique is widely used, because it is the simplest way (convenient, fast, and low cost) to prepare uniform organic cocrystals with regular morphology,w hich is essential for further characterization and application.…”

“…Liquid-phase techniques include liquid-liquid interfacial precipitation, [48] solvent vapor annealing, [49] reprecipitation, [25] drop-casting,a nd diffusion, which can produce cocrystals from adonor-acceptor mixed solution. [1] In comparison, vapor-phase methods are reported seldomly, [36] although they are essential for co-crystallizing of organics with poor solubilities.I nt hese methods,b oth co-sublimation and co-deposition should be performed, therefore insoluble molecules with similar sublimation points can be used. [1] In comparison, vapor-phase methods are reported seldomly, [36] although they are essential for co-crystallizing of organics with poor solubilities.I nt hese methods,b oth co-sublimation and co-deposition should be performed, therefore insoluble molecules with similar sublimation points can be used.…”

“…[4] However,t here are long-standing critical problems in this research field. [5,36] There are some excellent reviews about organic D-A complexes for novel organic electronics [37] and techniques/ methods of the preparation and characterization of organic cocrystals,a sw ell as some applications of cocrystals before 2016, [38a] thus in this Minireview,w eo nly make ab rief summary focusing on recent development and applications (except electrical conductivities and field-effect transistors (FETs)) of organic cocrystals including reducing the ACQ effect, tuning light emission, ferroelectricity and multiferroics, optical waveguides,a nd stimuli-responsiveness.W ea lso provide ad iscussion on current achievements,l imitations and perspectives.F inally,w et ry to aim at providing some useful instructions for further investigation of organic cocrystals. Secondly,t he relationships between crystal structures and the resulting performance,between the charge-transfer degree within cocrystals and the lattice stability, [33] optoelectronic,and photophysical properties, [34,35] as well as the mechanism of electronic interaction between building blocks remain elusive, [5] all of which greatly impedes regulating the properties of the cocrystals.T he effective tuning of cocrystals properties to give the desired functions by designing and controlling the stoichiometric ratio,m olecular stacking mode,o rientation, crystal phase and morphology is still at an early stage and remains achallenge.…”