scholarly journals Exciton transport in molecular organic semiconductors boosted by transient quantum delocalization

2022 ◽  
Author(s):  
Samuele Giannini ◽  
Wei-Tao Peng ◽  
Lorenzo Cupellini ◽  
Daniele Padula ◽  
Antoine Carof ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
Diffusion Constant ◽  
Reorganization Energy ◽  
Clear Correlation ◽  
Optoelectronic Materials ◽  
Surface Hopping ◽  
Exciton Transport ◽  
Organic Optoelectronic Devices ◽  
Organic Optoelectronic ◽  
Quantum Delocalization

Abstract Designing molecular materials with very large exciton diffusion lengths would remove some of the intrinsic limitations of present-day organic optoelectronic devices. Yet, the nature of excitons in these materials is still not sufficiently well understood. Here we present Frenkel exciton surface hopping, a highly efficient method to propagate excitons through truly nano-scale materials by solving the time-dependent Schrödinger equation coupled to nuclear motion. We find a clear correlation between diffusion constant and quantum delocalization of the exciton. In materials featuring some of the highest diffusion lengths to date, e.g. the non-fullerene acceptor Y6, the exciton propagates via a transient delocalization mechanism, reminiscent to what was recently proposed for charge transport. Yet, the extent of delocalization is rather modest, even in Y6, and found to be limited by the relatively large exciton reorganization energy. On this basis we chart out a path for rationally improving exciton transport in organic optoelectronic materials.

Theoretical Investigation of Structural Effects on the Charge Transfer Properties in Modified Phthalocyanines

MRS Advances ◽  
2015 ◽  
Vol 1 (7) ◽  
pp. 453-458 ◽  
Author(s):  
Patrick J. Dwyer ◽  
Stephen P. Kelty
Keyword(s):  
Organic Semiconductors ◽  
Electron Affinity ◽  
Density Functional ◽  
Reorganization Energy ◽  
High Electron ◽  
Optoelectronic Materials ◽  
Research Attention ◽  
Efficient Charge ◽  
Reorganization Energies ◽  
P Type

ABSTRACTFor efficient charge separation and charge transport in optoelectronic materials, small internal reorganization energies are desired. While many p-type organic semiconductors have been reported with low internal reorganization energies, few n-type materials with low reorganization energy are known. Metal phthalocyanines have long received extensive research attention in the field of organic device electronics due to their highly tunable electronic properties through modification of the molecular periphery. In this study, density functional theory (DFT) calculations are performed on a series of zinc-phthalocyanines (ZnPc) with various degrees of peripheral per-fluoroalkyl (-C3F7) modification. Introduction of the highly electron withdrawing groups on the periphery leads to a lowering in the energy of the molecular frontier orbitals as well as an increase in the electron affinity. Additionally, all molecules studies are found to be most stable in their anionic form, demonstrating their potential as n-type materials. However, the calculated internal reorganization energy slightly increases as a function of peripheral modification. By varying the degree of modification we develop a strategy for obtaining an optimal balance between low reorganization energy and high electron affinity for the development of novel n-type optoelectronic materials.

High-performance amorphous organic semiconductor-based vertical field-effect transistors and light-emitting transistors

Nanoscale ◽  
2020 ◽  
Vol 12 (35) ◽  
pp. 18371-18378 ◽  
Author(s):  
Haikuo Gao ◽  
Jinyu Liu ◽  
Zhengsheng Qin ◽  
Tianyu Wang ◽  
Can Gao ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
Field Effect ◽  
High Performance ◽  
Field Effect Transistors ◽  
Optoelectronic Devices ◽  
Light Emitting ◽  
Vertical Field ◽  
Organic Optoelectronic Devices ◽  
Organic Optoelectronic ◽  
Vertical Field Effect

Two kinds of vertical organic optoelectronic devices were constructed based on amorphous organic semiconductors and high device performances were achieved.

scholarly journals Revealing molecular conformation–induced stress at embedded interfaces of organic optoelectronic devices by sum frequency generation spectroscopy

2021 ◽  
Vol 7 (16) ◽  
pp. eabf8555
Author(s):  
Zhongwu Wang ◽  
Hongzhen Lin ◽  
Xi Zhang ◽  
Jie Li ◽  
Xiaosong Chen ◽  
...  
Keyword(s):  
Molecular Conformation ◽  
Optoelectronic Devices ◽  
Sum Frequency Generation ◽  
Interface Stress ◽  
Sum Frequency ◽  
Device Stability ◽  
Induced Stress ◽  
Organic Optoelectronic Devices ◽  
Organic Devices ◽  
Organic Optoelectronic

Interface stresses are pervasive and critical in conventional optoelectronic devices and generally lead to many failures and reliability problems. However, detection of the interface stress embedded in organic optoelectronic devices is a long-standing problem, which causes the unknown relationship between interface stress and organic device stability (one key and unsettled issue for practical applications). In this study, a kind of previously unknown molecular conformation–induced stress is revealed at the organic embedded interface through sum frequency generation (SFG) spectroscopy technique. This stress can be greater than 10 kcal/mol per nm2 and is sufficient to induce molecular disorder in the organic semiconductor layer (with energy below 8 kcal/mol per nm2), finally causing instability of the organic transistor. This study not only reveals interface stress in organic devices but also correlates instability of organic devices with the interface stress for the first time, offering an effective solution for improving device stability.

Surface Cleaning Challenges for Organic Light Emitting Diodes

2021 ◽  
Vol 314 ◽  
pp. 3-8
Author(s):  
Noel Giebink
Keyword(s):  
Light Emitting Diodes ◽  
Surface Cleaning ◽  
Organic Light Emitting Diodes ◽  
Large Area ◽  
Light Emitting ◽  
Organic Light ◽  
Organic Optoelectronic Devices ◽  
Soft Thin Film ◽  
Organic Optoelectronic

Organic optoelectronic devices such as light-emitting diodes and solar cells present unique challenges for surface cleaning and preparation because of their large area and the ‘soft’, thin film nature of the materials involved. This paper gives an introduction to this class of semiconductor devices and covers a recent example of how surface cleaning impacts the long-term reliability of organic light-emitting diodes being commercialized for solid-state lighting.

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