Recent Advances in Wide‐Bandgap Photovoltaic Polymers

Abstract

The past decade has witnessed significant advances in the field of organic solar cells (OSCs). Ongoing improvements in the power conversion efficiency of OSCs have been achieved, which were mainly attributed to the design and synthesis of novel conjugated polymers with different architectures and functional moieties. Among various conjugated polymers, the development of wide-bandgap (WBG) polymers has received less attention than that of low-bandgap and medium-bandgap polymers. Here, we briefly summarize recent advances in WBG polymers and their applications in organic photovoltaic (PV) devices, such as tandem, ternary, and non-fullerene solar cells. Addtionally, we also dissuss the application of high open-circuit voltage tandem solar cells in PV-driven electrochemical water dissociation. We mainly focus on the molecular design strategies, the structure-property correlations, and the photovoltaic performance of these WBG polymers. Finally, we extract empirical regularities and provide invigorating perspectives on the future development of WBG photovoltaic materials.

Phthalimide‐Based High Mobility Polymer Semiconductors for Efficient Nonfullerene Solar Cells with Power Conversion Efficiencies over 13%

“…Therefore, the BDT-based polymers typically show low motilities in neat films, as revealed by mobility measurement in organic thinfilm transistors (OTFTs). [47,48] Phthalimide (PhI), an imide-functionalized benzene, has been much less explored in the field of organic electronics, [49][50][51] in comparison to other imide-functionalized arenes. [27,46] In these senses, it is highly imperative to develop donor polymers based on new building blocks with distinct structure motifs to enrich the materials diversity, improve the charge transport property, and further enhance the PSC efficiency, which, additionally, provide new platforms for studying the fundamental materials structure-property correlations.…”

Recent Progress in Molecular Design of Fused Ring Electron Acceptors for Organic Solar Cells

“…Ie et al first developed conjugated polymers based on BDT and benzo‐[1,2‐c:4,5‐c′]dithiophene‐4,8‐dione (BDD) . Later, a series of wide bandgap BDT‐BDD polymers was developed by various groups . In 2016, Hou and co‐workers used wide bandgap polymer PBDB‐T ( E g opt of 1.80 eV and HOMO of –5.33 eV) with ITIC , a PCE of 11.21% was achieved exceeding the efficiency of FA‐based OSCs for the very first time .…”

Medium‐Bandgap Conjugated Polymer Donors for Organic Photovoltaics

“…In tandem devices, photons with low and high energy can be selectively harvested by the rear and front subcells . MBG or LBG polymers have been used in the rear subcell to absorb low energy photons, meanwhile, WBG polymers have been used in the front subcell to absorb high energy photons . Therefore, MBG polymers played an important role in the improvement of the performance of tandem OPV cells.…”

“…In 2017, Cai and co‐workers pioneered the “WBG,” “MBG,” “LBG” concepts about polymer donors. Generally, according to optical bandgap ( E g opt ), polymer donors can be categorized as low‐bandgap (LBG, E g opt < 1.6 eV), medium‐bandgap (MBG, 1.6 eV < E g opt < 1.8 eV), and wide‐bandgap (WBG, E g opt > 1.8 eV) polymers . Among the three types of polymer donors, MBG and LBG copolymers have attracted more attention because of the promising absorption properties which play key role in the OPV devices.…”