Improving Electron Transport in a Double-Cable Conjugated Polymer via Parallel Perylenetriimide Design

Abstract

Double-cable conjugated polymer can be applied to single-component organic solar cells (SCOSCs), which have great potential to improve the stability and to simplify the fabrication procedure compared to two-component organic solar cells. However, SCOSCs always show low power-conversion efficiencies (PCEs), which is mainly due to the difficulty to tune the nanophase separation in double-cable polymers for charge transport. Herein, we are able to find a way to improve the electron transport in double-cable polymers. The idea starts by introducing a parallel and large benzo­[ghi]­perylenetriimide into the side chains, different from the conventional perylene bisimide (PBI) side units in double-cable polymers. The new electron-deficient side units were found to lower the crystallinity of conjugated backbone and enhance the contact region between different acceptors. This could help in electron transport in the new double-cable polymers, as confirmed by space-charge limited current measurement. Therefore, the new double-cable polymer provided a high PCE of 4.34% in SCOSCs compared to 1.92% based on the polymer with PBI side units. Our results demonstrate that by rationally designing electron-deficient side units, the electron transport in double-cable polymers can be optimized toward efficient SCOSCs.

Significantly Improved Morphology and Efficiency of Nonhalogenated Solvent‐Processed Solar Cells Derived from a Conjugated Donor–Acceptor Block Copolymer

“…Over the past two decades, several research groups, including our own, have been studying new materials that covalently anchor the electron donor (D) and acceptor (A) moieties . PSCs bearing above‐mentioned materials have recently been studied in two main forms.…”

“…PSCs bearing above‐mentioned materials have recently been studied in two main forms. One is a double‐cabled polymer composed mainly of a small conjugated molecular acceptor bound to the side chains of a main chain conjugated polymer donor . The other is a conjugated block copolymer (CBCP) combining the donor block (DB) and the acceptor block (AB) in a polymer chain .…”

An Organic–Inorganic Hybrid Material Based on Benzo[ghi]perylenetri-imide and Cyclic Titanium-Oxo Cluster for Efficient Perovskite and Organic Solar Cells

“…BPTI unit as an π-extended PDI exhibits deep frontier energy levels and strong crystallinity, which can be potentially used as electron transporting material. [51] The targeted hybrid material CTOC-3-BPTI (Scheme 1) was simply synthesized via ligand exchange between BPTI-OH and ethylene glycolates in CTOC-3. CTOC-3-BPTI was then applied as interlayer into PSCs and OSCs, exhibiting enhanced PCEs over 20% and 16%.…”

Miscibility‐Controlled Phase Separation in Double‐Cable Conjugated Polymers for Single‐Component Organic Solar Cells with Efficiencies over 8 %

“…We have been particularly interested in double‐cable conjugated polymers for application in SCOSCs since they could be synthesized via a controllable manner, in which a series of functionalized monomers with pendent electron acceptors were prepared for palladium‐catalyzed polymerization [11] . This enabled us to incorporate the widely reported conjugated polymers and electron acceptors into double‐cable polymers, providing tunable optical and electrical properties [7h–m, 12] . Among them, we found that the linear conjugated backbones [7h] and post‐thermal treatment [7i] could facilitate the simultaneous self‐assembly of conjugated backbones and aromatic side units, generated well‐ordered nanophase separation, and hence provided external quantum efficiencies (EQEs) above 0.65 and PCEs over 6 %.…”