Chapter 15
π-Conjugated Polymers Incorporating
Naphthalene-Based Nitrogen-Containing
Heteroaromatics for Organic
Photovoltaics
Itaru Osaka
Abstract Recently, a wide variety of π-conjugated polymers have been developed
for the use as the active layer in organic photovoltaics (OPVs). This chapter will
summarize the recent development of π-conjugated polymers with donor–acceptor
motifs, specifically, based on naphthalene-based nitrogen-containing heteroaromatics as the acceptor unit. With the strong electron-deficient nature as well as
the large π-conjugation system, incorporation of these heteroaromatics in the backbone allows us to create π-conjugated polymers having wide absorption range, i.e.,
narrow bandgap, deep HOMO energy levels, and high crystallinity, all of which are
important for improving the efficiency of OPV cells. We describe the syntheses, properties, structural order in the thin films, and OPV performances of the π-conjugated
polymers based on naphthobisthiadiazole and its analogues.
Keywords -conjugated polymers · Semiconducting polymers · Donor–acceptor
polymers · Organic photovoltaics
15.1 Introduction
Over the past few decades, π-conjugated polymers have been widely studied as semiconducting materials owing to their good electrical and optical properties (Reynolds
et al. 2019). An important feature of π-conjugated polymers is that they can be
dissolved in organic solvents and thus can be solution-processed to form robust thin
films on both rigid and flexible substrates. This feature is beneficial for applications to organic devices, including organic light-emitting diodes (OLEDs) (Adachi
et al. 2019), organic field-effect transistors (OFETs)/organic thin-film transistors
(OTFTs) (Bao and Locklin 2007), and organic photovoltaics (OPVs)/organic solar
cells (OSCs) (Brabec et al. 2014). In particular, OPVs have recently been attracting
more attention than other devices due to the pressing need for renewable energy
sources.
I. Osaka (B)
Department of Applied Chemistry, Hiroshima University, Higashihiroshima, Japan
e-mail: iosaka@hiroshima-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2021
Y. Ooyama and S. Yagi (eds.), Progress in the Science of Functional Dyes,
https://doi.org/10.1007/978-981-33-4392-4_15
541
π-Conjugated Polymers Incorporating
Naphthalene-Based Nitrogen-Containing
Heteroaromatics for Organic
Photovoltaics
Itaru Osaka
Abstract Recently, a wide variety of π-conjugated polymers have been developed
for the use as the active layer in organic photovoltaics (OPVs). This chapter will
summarize the recent development of π-conjugated polymers with donor–acceptor
motifs, specifically, based on naphthalene-based nitrogen-containing heteroaromatics as the acceptor unit. With the strong electron-deficient nature as well as
the large π-conjugation system, incorporation of these heteroaromatics in the backbone allows us to create π-conjugated polymers having wide absorption range, i.e.,
narrow bandgap, deep HOMO energy levels, and high crystallinity, all of which are
important for improving the efficiency of OPV cells. We describe the syntheses, properties, structural order in the thin films, and OPV performances of the π-conjugated
polymers based on naphthobisthiadiazole and its analogues.
Keywords -conjugated polymers · Semiconducting polymers · Donor–acceptor
polymers · Organic photovoltaics
15.1 Introduction
Over the past few decades, π-conjugated polymers have been widely studied as semiconducting materials owing to their good electrical and optical properties (Reynolds
et al. 2019). An important feature of π-conjugated polymers is that they can be
dissolved in organic solvents and thus can be solution-processed to form robust thin
films on both rigid and flexible substrates. This feature is beneficial for applications to organic devices, including organic light-emitting diodes (OLEDs) (Adachi
et al. 2019), organic field-effect transistors (OFETs)/organic thin-film transistors
(OTFTs) (Bao and Locklin 2007), and organic photovoltaics (OPVs)/organic solar
cells (OSCs) (Brabec et al. 2014). In particular, OPVs have recently been attracting
more attention than other devices due to the pressing need for renewable energy
sources.
I. Osaka (B)
Department of Applied Chemistry, Hiroshima University, Higashihiroshima, Japan
e-mail: iosaka@hiroshima-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2021
Y. Ooyama and S. Yagi (eds.), Progress in the Science of Functional Dyes,
https://doi.org/10.1007/978-981-33-4392-4_15
541