Pressure-Induced Enhancement of Thermoelectric Performance in Rubrene

Abstract

In this work, the thermoelectric performance of a typical small-molecule organic semiconductor rubrene under different hydrostatic pressures was studied by first-principles calculation and molecular dynamics simulation. The ZT value of rubrene can reach 1.6 at 400 K due to an unprecedented increase in hole mobility under hydrostatic pressure. The underlying mechanism is ascribed to the suppression of low-frequency phonons (which weakens electron−phonon scattering) and the increase in the intermolecular electronic coupling. The effect of uniaxial stress has also been investigated to confirm this conclusion. Our results provide meaningful insights to understand the relationship between thermoelectric properties and hydrostatic pressure in organic semiconductors.

The Zintl phase compounds AEIn2As2 (AE = Ca, Sr, Ba): topological phase transition under pressure

“…31,32 In a word, due to its low cost and ease of operation, external pressure is widely used in experimental studies. And the introduction of pressure often leads to interesting and important potential properties, such as thermoelectric performance control, 33 structural phase transition, 29,[34][35][36][37] metal-insulator phase transitions with band gap changes [38][39][40][41] and topological phase transitions with band inversion. [29][30][31][32][42][43][44][45][46][47] Obviously, as a novel material, many physical properties of AEIn 2 As 2 (AE = Ca, Sr, Ba) are not yet known.…”

Strain-induced thermoelectricity in pentacene

“…However, for a pure pentacene molecule, ZT is close to one 15 , which is still far beyond the level of meeting the practical applications. Nevertheless, significant progress has been made in developing high-performance TE devices using organic molecules by employing various strategies like chemical doping [16][17][18] , field-modulated doping [19][20][21] , and strain 22 .…”

“…Due to the presence of weak Van der Waals interaction, these organic molecules easily undergo lattice deformation under the application of external force 24,25 . Thus, as a non-synthetic strategy, introducing strain in such molec-ular junction could be an efficient way to improve the TE performance 22 . For example, in case of TIPS (triisopropylsilyly-ethynyl) pentacene, carrier mobility increases from 0.8 to 4.6 cm 2 V −1 s −1 when the π − π stacking distance is decreased from 3.33 Å to 3.08 Å26 .…”

Strain-induced thermoelectricity in pentacene

“…Nevertheless, significant progress has been made in developing high-performance TE devices using organic molecules by employing various strategies like chemical doping, 16–18 field-modulated doping, 19–21 and strain. 22…”

“…Nevertheless, significant progress has been made in developing highperformance TE devices using organic molecules by employing various strategies like chemical doping, [16][17][18] field-modulated doping, [19][20][21] and strain. 22 It turns out that carrier mobility is one of the key factors to determine the TE response. For small organic molecules like pentacene, the inter-molecular packing and molecular structure become decisive to the carrier mobility 23,24 and hence the TE performance.…”