ポリマー・フラーレンの混合太陽電池における熱エクシトンの解離と対比して,電荷移転状態
Jiye Lee1, Koen Vandewal, Shane R Yost
1Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|August 10, 2010
まとめ
ホットエクシトンの解離は,ポリマーフルレンの太陽電池に最小限の影響を及ぼします. 研究によると,内部量子産量は,エキソンと直接の電荷移転刺激に類似しており,熱プロセスは有意ではないことを示唆しています.
科学分野:
- マテリアルサイエンス 材料科学
- フォトボルトイカは,太陽光発電です.
- 物理化学 物理化学
背景:
- ポリマーフルレンの太陽電池は,再生可能エネルギーの重要な技術です.
- エクシトンの解離は,光を電気に変換する上で重要なステップです.
- ホットエクシトンの解離は,効率的な電荷生成のための提案されたメカニズムです.
研究 の 目的:
- 原型ポリマーフラーレン太陽電池における熱エクシトン解離の役割を調査する.
- 熱処理がキャリア光生成に有意に寄与するかどうかを判断する.
- 熱いエクシトン解離の効率を,直接の電荷移転エクシテーションと比較するために.
主な方法:
- 2つの原型ポリマー・フルレン混合太陽電池の実験分析.
- キャリア光生成のための内部量子収率の測定.
- 電流-電圧特性の温度依存性の分析.
主要な成果:
- 内部量子産量は,エキソンと直接の電荷移転状態刺激の両方に対して類似していることが判明しました.
- 電流-電圧特性の温度依存は,熱エクシトンの解離による影響は軽微であることを示した.
- ホットエクシトンの解離は,これらのシステムにおける電荷生成の主要な経路ではないようです.
結論:
- ポリマー・フルレンの太陽電池における熱エクシトンの解離の意義は無視できる.
- 充電生成は主に確立された経路を通して起こりますが,ホットエクシトンの解離ではありません.
- 代替メカニズムや材料システムの探求のためにさらなる研究が必要になる可能性があります.
さらに関連する動画
関連する概念動画
01:11P-N junction
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...
01:26Photochemical Electrocyclic Reactions: Stereochemistry
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
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
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.
01:22Carrier Generation and Recombination
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...
01:30The Electrical Double Layer
In the region where two bulk phases meet, an intricate electric charge distribution arises due to charge transfer, ion adsorption, molecular orientation, and charge distortion. This complex distribution is commonly referred to as the electrical double layer.When a solid electrode interfaces with ions in an electrolyte solution, the speed of electron transfer dictates the rates of oxidation and reduction. The electrode acquires a charge through the escape of atoms into the solution as cations or...
01:17Thermal Electrocyclic Reactions: Stereochemistry
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.