Near-Infrared All-Fused-Ring Nonfullerene Acceptors Achieving an Optimal Efficiency-Cost-Stability Balance in Organic Solar Cells

Synergistically achieving stability, cost, and efficiency is crucial for the commercialization of organic solar cells (OSCs). Despite the rapid development of 2 (3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile-type nonfullerene acceptors (NFAs), they are inherently unstable due to the vulnerable exocyclic double bond and possess high synthesis complexity (SC). Based on the all-fused-ring electron acceptor (AFAR) concept, we report two new near-infrared NFAs, F11 and F13, featuring all fused dodecacyclic rings. By developing a whole set of synthetic procedures, F11 and F13 can be conveniently prepared at a 10 g scale within a notably short period, displaying both the low SC and the lowest costs among reported NFAs, even comparable to the classical photovoltaic material, P3HT. In comparison with the one-dimensional stacking of ITYM (ITYM = 2,2 '-(7,7,15,15-tetrahexyl-7,15-dihydro-s-indaceno[1,2-b:5,6-b ']diindeno[1,2-d]thiophene-2,10(2H)-diylidene) dimalononitrile), the first AFRA, and mixed J- and H-aggregations in Y6, F-acceptors show a compact honeycomb-type three-dimensional stacking with exclusive J-aggregations, favoring multichannel charge transport. By matching a medium-bandgap polymer donor, F13 delivers greater than 13% power conversion efficiencies, which is the highest performance among non-INCN acceptors, and shows device stability superior to the typical ITIC-and Y6-based OSCs as evidenced by the negligible burn-in losses. This work presents a first and successful example of NFAs achieving an optimal efficiency-cost-stability balance in OSCs.

Automated summary

This study successfully developed two new near-infrared nonfullerene acceptors, F11 and F13, which achieved a synergistic balance of stability, cost, and efficiency in organic solar cells (OSCs). These acceptors have low complexity and cost, and show advantages in charge transport.