Benzodithiophenedione-based polymers: recent advances in organic photovoltaics

Over the past 20 years, significant progress has been made in organic photovoltaics (OPVs) due to its advantages of being cost-effective, being lightweight, and having flexible manufacturability. The optical-active layer of OPVs consists of a p -type polymer as the donor and an n -type small molecule as the acceptor. An efficient design strategy of a polymer donor is based on an alternating electron-donating unit (D) and an electron-accepting unit (A). Among numerous electron-accepting units, an emerging annelated thiophene of benzodithiophenedione (BDD) has exhibited a distinguished photovoltaic performance because of its planar molecular structure, low-lying highest occupied molecular orbit (HOMO) level and good self-assembly property. In this review article, we summarize the most recent developments in BDD-based photovoltaic materials. Special attention is paid to the chemical structure-property relationships, such as the absorption, bandgap, energy levels, mobilities, and photovoltaic performances. The empirical regularities and perspectives on the future development of BDD-based photovoltaic materials are included. Photovoltaics: An organic solution Development of a polymer that has exciting potential for solar-energy conversion has been reviewed by researchers in China. Traditional solar cells are made using silicon, but their efficiency has not yet reached a level where they can compete with fossil fuels. In the last few decades, organic solar cells have emerged as an alternative, offering simpler fabrication and lighter, cost-effective and flexible devices. Lijun Huo from Beihang University, Beijing, and colleagues summarise recent progress in organic photovoltaic cells made using benzodithiophenedione (BDD) based polymeric donors. The authors review the properties of this kind of material that are key to optimising photovoltaic performance such as optical absorption, the electron energy levels, the charge mobility, the crystallinity and morphology. Careful control of these properties has enabled BDD-based devices to achieve power conversion efficiencies of over 15%. An emerging annelated thiophene of benzodithiophenedione (BDD) has exhibited its distinguished photovoltaic performance since its planar molecular structure, low-lying highest occupied molecular orbit (HOMO) level and well self-assembly property. In recent 7 years, BDD-based polymer donor have shown a rapid and incredible advancement by utilizing different acceptor materials. Consideri