Free-Charge Carrier Generation in Homojunction Non-Polymeric Organic Semiconductor Films – The Role of the Optical Frequency Dielectric Constant

IF 8 2区 材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY
Neil Mallo, Shaun McAnally, Hui Jin, Eucalyptus Brooks, Ronan Chu, Mohammad Babazadeh, James Smyth, David M. Huang, Nicholas Hight-Huf, Obadiah G. Reid, Garry Rumbles, Paul L. Burn, Ian R. Gentle, Paul E. Shaw
{"title":"Free-Charge Carrier Generation in Homojunction Non-Polymeric Organic Semiconductor Films – The Role of the Optical Frequency Dielectric Constant","authors":"Neil Mallo,&nbsp;Shaun McAnally,&nbsp;Hui Jin,&nbsp;Eucalyptus Brooks,&nbsp;Ronan Chu,&nbsp;Mohammad Babazadeh,&nbsp;James Smyth,&nbsp;David M. Huang,&nbsp;Nicholas Hight-Huf,&nbsp;Obadiah G. Reid,&nbsp;Garry Rumbles,&nbsp;Paul L. Burn,&nbsp;Ian R. Gentle,&nbsp;Paul E. Shaw","doi":"10.1002/adom.202401825","DOIUrl":null,"url":null,"abstract":"<p>Engineering the dielectric constant (<i>ε</i>) to lower the exciton binding energy of the light-absorbing semiconductor can improve organic photovoltaic (OPV) device performance. Here, a series of materials are reported with 2-(3-oxo-2,3-dihydro-1<i>H</i>-inden-1-ylidene)malononitrile (INCN) acceptor end groups and a central glycolated bis(4<i>H</i>-cyclopenta[2,1-<i>b</i>:3,4-<i>b</i>′]dithiophene) unit with large low-frequency (<i>ε</i><sub>lf</sub> = 7.4–7.9 at 0.1–0.2 MHz) and optical-frequency (<i>ε</i><sub>opt</sub> up to 6.6 at 2 × 10<sup>14</sup> Hz) dielectric constants. The INCN end groups differed in whether they were protonated, chlorinated, or fluorinated, with the latter having the highest <i>ε</i><sub>opt</sub>. An <i>ε</i><sub>opt</sub> of 6.6 is predicted to lead to a low exciton binding energy of ≈0.04 eV. Time-resolved microwave conductivity measurements showed a temperature-dependent yield–mobility product, with it increasing linearly from 340 K. The onset temperature was near that required to overcome the calculated exciton binding energy and indicates increased free charge generation in a homojunction film. Room temperature transient absorption spectroscopy revealed that photoexcitation rapidly converted to a lower energy state that was consistent with the formation of polarons or a charge transfer state. This work provides experimental evidence of the importance of <i>ε</i><sub>opt</sub> for the generation of free charges, and a strategy for development of efficient single chromophore homojunction OPV devices.</p>","PeriodicalId":116,"journal":{"name":"Advanced Optical Materials","volume":"12 36","pages":""},"PeriodicalIF":8.0000,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Advanced Optical Materials","FirstCategoryId":"88","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/adom.202401825","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0

Abstract

Engineering the dielectric constant (ε) to lower the exciton binding energy of the light-absorbing semiconductor can improve organic photovoltaic (OPV) device performance. Here, a series of materials are reported with 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (INCN) acceptor end groups and a central glycolated bis(4H-cyclopenta[2,1-b:3,4-b′]dithiophene) unit with large low-frequency (εlf = 7.4–7.9 at 0.1–0.2 MHz) and optical-frequency (εopt up to 6.6 at 2 × 1014 Hz) dielectric constants. The INCN end groups differed in whether they were protonated, chlorinated, or fluorinated, with the latter having the highest εopt. An εopt of 6.6 is predicted to lead to a low exciton binding energy of ≈0.04 eV. Time-resolved microwave conductivity measurements showed a temperature-dependent yield–mobility product, with it increasing linearly from 340 K. The onset temperature was near that required to overcome the calculated exciton binding energy and indicates increased free charge generation in a homojunction film. Room temperature transient absorption spectroscopy revealed that photoexcitation rapidly converted to a lower energy state that was consistent with the formation of polarons or a charge transfer state. This work provides experimental evidence of the importance of εopt for the generation of free charges, and a strategy for development of efficient single chromophore homojunction OPV devices.

Abstract Image

同结非聚合物有机半导体薄膜中自由电荷载流子的产生——光频率介电常数的作用
设计介电常数(ε)来降低光吸收半导体的激子结合能,可以改善有机光伏(OPV)器件的性能。本文报道了一系列具有2-(3-氧-2,3-二氢- 1h -茚-1-乙基)丙二腈(INCN)受体端基和中心糖基化的双(4h -环五[2,1-b:3,4-b ']二噻吩)单元的材料,它们具有较大的低频(0.1-0.2 MHz时εlf = 7.4-7.9)和光频(2 × 1014 Hz时εopt高达6.6)介电常数。INCN端基团的差异在于它们是质子化的、氯化的还是氟化的,后者具有最高的εopt。εopt为6.6时,激子结合能较低,约为0.04 eV。时间分辨微波电导率测量显示出与温度相关的产率迁移率产品,从340 K开始线性增加。开始温度接近于克服计算出的激子结合能所需的温度,表明在同结膜中自由电荷的产生增加。室温瞬态吸收光谱显示,光激发迅速转化为较低的能态,这与极化子的形成或电荷转移态一致。这项工作提供了ε选择对自由电荷产生的重要性的实验证据,并为开发高效的单色团同质结OPV器件提供了策略。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 求助全文
来源期刊
Advanced Optical Materials
Advanced Optical Materials MATERIALS SCIENCE, MULTIDISCIPLINARY-OPTICS
CiteScore
13.70
自引率
6.70%
发文量
883
审稿时长
1.5 months
期刊介绍: Advanced Optical Materials, part of the esteemed Advanced portfolio, is a unique materials science journal concentrating on all facets of light-matter interactions. For over a decade, it has been the preferred optical materials journal for significant discoveries in photonics, plasmonics, metamaterials, and more. The Advanced portfolio from Wiley is a collection of globally respected, high-impact journals that disseminate the best science from established and emerging researchers, aiding them in fulfilling their mission and amplifying the reach of their scientific discoveries.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信