Harnessing the Structure‐Performance Relationships in Designing Non‐Fused Ring Acceptors for Organic Solar Cells

Abstract

The prerequisite for commercially viable organic solar cells (OSC) is to reduce the efficiency‐stability‐cost gap. Therefore, the cost of organic materials should be reduced by minimizing the synthetic steps, yet maintaining the molecular planarity and efficiencies achieved by the fused ring acceptors (FRA). In this respect, developing non‐fused ring acceptors (NFRA) with suitable functionalization to favor conformational planarity and effective molecular packing is beneficial and cost‐effective. Presently, the power conversion efficiency (PCE) for NFRAs is around 16 %, yet lower than the 19 % achieved for FRAs. Despite their potential, a thorough understanding of the effective structural design of NFRAs is necessary for developing efficient OSCs. This article pays special attention to the molecular design concept for NFRAs developed in the last years and analyzed the approach toward materials design and efficiency improvement, an important step toward technological application.

A facile synthetic approach based on thieno[3,4-c]pyrrole-4,6-dione to construct polymer donors for highly efficient organic solar cells

“…Based on the abovementioned insights, many efforts and breakthroughs have been made in the development of low-cost active layer materials, such as non-fused ring small molecule acceptors (SMAs) 20,24,25 and polythiophene derivative donors. [26][27][28] However, the PCEs of the relevant OSC systems have rarely exceeded 17%, [29][30][31][32] while at the same time, the development of new and simple A-units combined with benzo[1,2-b:4,5-b 0 ]dithiophene-thiophene (BDT-T) derivatives to develop cost-efficient polymer donors (P D s) has increasingly garnered attention as a viable alternative. [33][34][35][36] For instance, Duan et al recently reported a building block, namely 3-cyanothiophene (CT), and further synthesized a donor polymer PBCT-2F based on the CT unit, which exhibited a remarkable PCE of 17.1%.…”

Diketopyrrolopyrrole-Coumarin Conjugates for Efficient Binary Organic Solar Cells

“…At present, in all the efficient OSCs, the donors used are conjugated copolymers; however, these copolymers have many disadvantages, such as batch-to-batch product variation, difficult purifications, and high cost, which limit the commercialization of OSCs. As compared to the polymeric donor, small molecules exhibit distinct advantages of monodispersed molecular backbones with low batch-to-batch variation and could be advantageous for device applications. − A recent investigation has shown that the all-small-molecule OSCs have attained PCEs in the range of 16–17% for small areas − and 10.65% for 1 cm 2 large-area OSC processed by slot die-coating, which is comparable to OSCs based on the copolymer as a donor, indicating the potential of OSCs based on small-molecule donors.…”

Additive engineering for high-performance P3HT:non-fused ring electron acceptor organic solar cell

“…Recently, researchers have shifted their focus to newly developed non-fused ring electron acceptors (NFREAs) due to their easy synthesis, low cost, and diverse molecular structures. 22–31 Some of these NFREAs, including high-performance NFREAs developed in our lab, have demonstrated PCEs over 15%, 24,26,32–34 making them potentially suitable for use with P3HT due to their tunable energy levels and energy bandgap. However, only few studies have investigated P3HT:NFREA blends due to their low PCE, and straightforward approaches to control phase separation in the blend film and optimize P3HT-based OSCs are rare.…”