内热电荷分离在非富勒伦受体/聚合物批量异质连接中自发发生
Kushal Rijal1, Neno Fuller1, Fatimah Rudayni1,2
1Department of Physics and Astronomy, University of Kansas, Lawrence, KS, 66045, USA.
Advanced materials (Deerfield Beach, Fla.)
|May 19, 2024
概括
有机光伏 (OPV) 与非富勒受体 (NFAs) 实现高效率. 这些设备中的电荷分离是由驱动的,而不是仅仅是能量,这是由于薄膜形态和电子移位.
科学领域:
- 材料科学 材料科学 材料科学
- 物理化学 物理化学
- 有机电子 有机电子
背景情况:
- 使用非富勒烯接受器 (NFAs) 的有机光伏 (OPV) 显示了接近20%的功率转换效率.
- 在NFA OPV中,高效的电荷载体生成发生,尽管在捐赠/接受器接口的能量抵消最小.
- 在NFAs中实现高效的电荷分离 (CS) 与低能耗的机制尚未完全理解.
研究的目的:
- 为了研究PM6:Y6批量异质连接中的电荷分离 (CS) 过程.
- 阐明非富勒烯接受器有机光伏在高效电荷生成背后的驱动力.
主要方法:
- 使用时间分辨率的两光子光辐射光谱学.
- 该研究的重点是PM6:Y6批量异质连接系统.
主要成果:
- 电荷分离 (CS),即将束电荷转移 (CT) 激子转化为自由载体,被确定为具有0.15 eV力屏障的内热过程.
- 自发的CS发生,尽管内热性质,表明一个的驱动力.
- 薄膜形态和PM6:Y6中的异构电子移位限制了刺激波函数,最大限度地增加了对CS的热贡献.
结论:
- 在电荷分离过程中,NFA OPV 的效率受到电荷分离过程中的性因素的显著影响.
- 优化膜形态和理解电子特性对于提高NFA OPV性能至关重要.
- 由率驱动的电荷分离为设计高效有机太阳能电池提供了一个新的范式.
相关概念视频
01:11P-N junction
519
A p-n junction is formed when p-type and n-type semiconductor materials are joined together. At the interface of the p-n junction, holes from the p-side and electrons from the n-side begin to diffuse into the opposite sides due to the concentration gradient. This diffusion of carriers leads to a region around the junction where there are no free charge carriers, known as the depletion region. The charge density within the depletion region for the n-side and p-side can be described by the...
519
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
2.3K
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
2.3K
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.0K
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
2.0K
01:26Photochemical Electrocyclic Reactions: Stereochemistry
1.8K
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
1.8K
01:22Carrier Generation and Recombination
565
Carrier generation is the process by which electron-hole pairs (EHPs) are created within the semiconductor. In direct-bandgap semiconductors, such as gallium arsenide (GaAs), this occurs efficiently when energy absorption prompts valence electrons to leap into the conduction band, leaving behind holes.
This process is given by the generation rate G and is efficient due to the conservation of momentum between the valence band maximum and conduction band minimum.
Indirect generation involves an...
This process is given by the generation rate G and is efficient due to the conservation of momentum between the valence band maximum and conduction band minimum.
Indirect generation involves an...
565
00:57Cationic Chain-Growth Polymerization: Mechanism
2.3K
The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the...
2.3K