Multistep nucleation and growth mechanisms of organic crystals from amorphous solid states

Abstract

Molecular self-assembly into crystallised films or wires on surfaces produces a big family of motifs exhibiting unique optoelectronic properties. However, little attention has been paid to the fundamental mechanism of molecular crystallisation. Here we report a biomimetic design of phosphonate engineered, amphiphilic organic semiconductors capable of self–assembly, which enables us to use real-time in-situ scanning probe microscopy to monitor the growth trajectories of such organic semiconducting films as they nucleate and crystallise from amorphous solid states. The single-crystal film grows through an evolutionary selection approach in a two-dimensional geometry, with five distinct steps: droplet flattening, film coalescence, spinodal decomposition, Ostwald ripening, and self-reorganised layer growth. These sophisticated processes afford ultralong high-density microwire arrays with high mobilities, thus promoting deep understanding of the mechanism as well as offering important insights into the design and development of functional high-performance organic optoelectronic materials and devices through molecular and crystal engineering.

Room‐Temperature Formation Pathway for CdTeSe Alloy Magic‐Size Clusters

“…With relevance to ternary perovskite MSCs, Equation (1) (Steps 1 and 2) provides a deeper understanding for these transformations among the various types of binary ME MSCs . The present findings on the room‐temperature evolution of CdTeSe MSC‐399 with mixed binary CdTe and CdSe induction period samples offer strong evidence support for the two‐pathway model proposed for binary semiconductor quantum dots and MSCs, and contribute to the advance of the nonclassical multistep nucleation models …”

“…The advance in the synthesis of quantum dots, resulting in an in‐depth understanding of the induction period described by the two‐pathway model, facilitates the control of size and particle yield of quantum dots, and thus embraces the promise of colloidal semiconductor quantum dots in various application areas . Furthermore, this two‐pathway model reinforces the multistep nucleation model which has been proposed for several other material systems including organics, polymers, inorganics, and metals …”

Room-temperature formation of CdS magic-size clusters in aqueous solutions assisted by primary amines

“…The multistep model, designated by nonclassical nucleation theory, accounts for the presence of intermediates in the pre-nucleation stage . Such intermediates have been illustrated in several materials systems including calcium-based inorganics [4][5][6][7][8] , organics [9][10][11] , polymers [12][13][14] , metals [15][16][17] , and semiconductor quantum dots (QDs) [18][19][20][21][22][23][24][25][26][27][28] .…”

Stability of organic thin-film transistors based on ultrathin films of dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT)

“…This can be considered similar to the Ostwald ripening process often observed during annealing processes, where large, stable droplets grow at the expense of smaller, less stable droplets. 40 While temporal morphological changes have been observed also for thick DNTT films (with a nominal thickness of 40 nm), 33 these occur on much larger time scales of weeks or months, due to the substantially larger mass transport involved in such thick films, and will not be discussed in this work. Here we investigate how the spontaneously occurring structural reconfiguration of ultrathin DNTT films affects the electrical characteristics of TFTs based on such films and explore the extent to which it can be prevented by cryogenic cooling or insitu encapsulation.…”