Novel Star-Shaped Helical Perylene Diimide Electron Acceptors for Efficient Additive-Free Nonfullerene Organic Solar Cells

Abstract

Two star-shaped helical perylene diimide (PDI) electron acceptors TPDI2 and FTPDI2 were designed and synthesized for nonfullerene organic solar cells (OSCs). The integration of helical PDIs into a three-dimensional structure provides a new strategy to tune the intermolecular interactions, and the as-cast blend films with PTB7-Th show favorable morphology as well as efficient charge transfer and separation, as evidenced by the morphology and femtosecond transient absorption (fs-TA) spectroscopy studies. A trade-off between suppressing the self-aggregation and maintaining the charge-transfer properties was achieved by FTPDI2. Using PTB7-Th as the electron donor, the FTPDI2-based nonfullerene OSCs show a high power conversion efficiency of 8.28%, without the assistance of any additives.

Progress in the synthesis of perylene bisimide dyes

“…This compound was used as an acceptor material in polymer solar cells showing a PCE of around 8%. 208 Similarly, related 3D nanostructures with a central triptycene core and molecular weights up to 6500 Da could be synthesized by Nuckolls and co-workers by light-induced fusion of PBI nanoribbons at the triptycene unit in the presence of iodine. These novel materials were used as electron-extracting layers in perovskite solar cells.…”

“…Accordingly, the protocol was adapted to the synthesis of polymers with ethylene-fused dimeric PBI repeat units 150,151 and as building blocks for large arrays composed of fused PBI units. 208 The latter compound as well as Nuckolls' tetrameric ribbon 233 and naphthoperylenediimide-vinylene polymer 150,213 showed high potential for application in polymer OSCs as acceptor materials leading to PCEs above 8%.…”

Chalcogen‐Fused Perylene Diimides‐Based Nonfullerene Acceptors for High‐Performance Organic Solar Cells: Insight into the Effect of O, S, and Se

“…Indeed, PDI derivatives are the earliest and most common NFAs, which generally exhibit strong electron‐accepting capability, strong absorption, high electron mobility on par with those of FAs, and excellent thermal and oxidative stability . Despite the aforementioned strengths, PDI acceptors tend to form large aggregates due to their large planar structures, which presumably bring out severe geminate recombination and excessive domain sizes, thus leading to detrimental effects to device performances . A proved strategy to circumvent the issue is constraining two or more PDIs to be nonplanar and/or the incorporation of a conjugated bridge .…”

“…[55][56][57] Despite the aforementioned strengths, PDI acceptors tend to form large aggregates due to their large planar structures, which presumably bring out severe geminate recombination and excessive domain sizes, thus leading to detrimental effects to device performances. [58][59][60][61][62] A proved strategy to circumvent the issue is constraining two or more PDIs to be nonplanar and/or the incorporation of a conjugated bridge. [63][64][65] In addition, versatile twisted structures such as PDI dimers, trimers, or tetramers through connecting the N, α, or β positions have been reported.…”

Indeno[1,2-b]thiophene End-capped Perylene Diimide: Should the 1,6-Regioisomers be systematically considered as a byproduct?

“…To tackle this problem, important efforts have been devoted to functionalize the peripheral positions, namely the bay (1,6,7,12) and ortho positions (2,5,8,11) 3,9,[15][16][17][18] , leading to profuse design principles and above all, to a better understanding of the structure-property relationships (Fig. 1) [19][20][21][22][23][24][25][26][27][28] .…”