Optical Characterization of the Hole Polaron in a Series of Diketopyrrolopyrrole Polymers Used for Organic Photovoltaics

Polymers

Evan L. Williams¹  Ter Shien Ang³  Zien Ooi¹  Prashant Sonar¹  Ting Ting Lin¹  Wei Teng Neo¹  Jing Song¹  Jonathan Hobley² 

[1] Agency for Science, Technology and Research, Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602, Singapore; E-Mails:;Department of Chemistry, Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong, BE 1410, Brunei; E-Mail:;National Junior College, 37 Hillcrest Road, Singapore 288913, Singapore; E-Mail:

关键词: organic solar cell;    organic photovoltaic;    diketopyrrolopyrrole;    chemical doping;    spectroelectrochemistry;    photoinduced absorption;    hole polaron;   

DOI  :  10.3390/polym7010069

来源: mdpi

【 摘 要 】

A strategy that is often used for designing low band gap polymers involves the incorporation of electron-rich (donor) and electron-deficient (acceptor) conjugated segments within the polymer backbone. In this paper we investigate such a series of Diketopyrrolopyrrole (DPP)-based co-polymers. The co-polymers consisted of a DPP unit attached to a phenylene, naphthalene, or anthracene unit. Additionally, polymers utilizing either the thiophene-flanked DPP or the furan-flanked DPP units paired with the naphthalene comonomer were compared. As these polymers have been used as donor materials and subsequent hole transporting materials in organic solar cells, we are specifically interested in characterizing the optical absorption of the hole polaron of these DPP based copolymers. We employ chemical doping, electrochemical doping, and photoinduced absorption (PIA) studies to probe the hole polaron absorption spectra. While some donor-acceptor polymers have shown an appreciable capacity to generate free charge carriers upon photoexcitation, no polaron signal was observed in the PIA spectrum of the polymers in this study. The relations between molecular structure and optical properties are discussed.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.