Electron Acceptors Based on α-Substituted Perylene Diimide (PDI) for Organic Solar Cells

Abstract

Perylene diimide (PDI) derivatives functionalized at the ortho-position (αPPID, αPBDT) were synthesized and used as electron acceptors in non-fullerene organic photovoltaic cells. Because of the good planarity and strong πstacking of ortho-functionalized PDI, the αPPID and αPBDT exhibit a strong tendency to form aggregates, which endow the materials with high electron mobility. The inverted OPVs employing αPDI-based compounds as the acceptors and PBT7-Th as the donor give the highest power conversion efficiency (PCE) values: 4.92% for αPBDT-based devices and 3.61% for αPPID-based devices, which are, respectively, 39% and 4% higher than that of their β-substituted counterparts βPBDT and βPPID. Charge separation studies show more efficient exciton dissociation at interfaces between αPDI-based compounds and PTB7-Th. The results suggest that α-substituted PDI derivatives are more promising electron acceptors for organic photovoltaic (OPV) components than β-isomers.

Recent Advances in Nonfullerene Acceptors for Organic Solar Cells

“…Due to the higher LUMO level of the acceptor and the deeper HOMO level of the donor, this photoactive material demonstrated a very high V oc of 1.3 V with an excellent PCE of 6.0% after the treatment of a mixed solvent additive of 0.5% N ‐methyl pyrrolidone and 0.5% diphenyl ether . Recently, two new coplanar nonfullerene small molecule acceptors A4 and A5 were developed by Yu and co‐workers, in which the two PDI molecules were linked by the benzodithiophene (BDT) bridges at the different bay position. The best PCE performance of this photoactive material based on the A4 acceptor was 4.92%, which was much higher than that of the A5 acceptor (3.61%).…”

Unraveling the efficiency-limiting morphological issues of the perylene diimide-based non-fullerene organic solar cells

“…One class of non-fullerene electron accepting materials is low-cost PDI derivatives 7,9–13 . The BHJ photoactive layer made with PDIs offers a high absorption coefficient in the visible region, good photochemical stability, and good thin film forming properties 7,9,14,15 . Despite their attractive features, PDI-based acceptors have met with little success, and few PDI systems have shown PCEs just over 8% 16,17 .…”

9,9′‐Bifluorenylidene‐Core Perylene Diimide Acceptors for As‐Cast Non‐Fullerene Organic Solar Cells: The Isomeric Effect on Optoelectronic Properties

“…[4,5] However, small-molecule acceptors based on PDIs have ag reat tendency to form self-aggregation and severe phase separation. [7] Since PDIs were developed as excellent units of non-fullerene acceptors, extensive efforts have been devoted to design all kinds of molecules to suppress intermoleculara ggregation of the PDI units. [7] Since PDIs were developed as excellent units of non-fullerene acceptors, extensive efforts have been devoted to design all kinds of molecules to suppress intermoleculara ggregation of the PDI units.…”