Simple Nonfused‐Ring Electron Acceptors with Noncovalently Conformational Locks for Low‐Cost and High‐Performance Organic Solar Cells Enabled by End‐Group Engineering

Abstract

The rapid advance of fused‐ring electron acceptors (FREAs) has greatly promoted the leap‐forward development of organic solar cells (OSCs). However, the synthetic complexity of FREAs may be detrimental for future commercial applications. Recently, nonfused‐ring electron acceptors (NREAs) have been developed to be a promising candidate to maintain a rational balance between cost and performance, of which the cores are composed of simple fused rings (NREAs‐I) or nonfused rings (NREAs‐II). Moreover, “noncovalently conformational locks”, are used as an effective strategy to enhance the rigidity and planarity of NREAs and improve device performance. Herein, a novel series of NREAs‐II (PhO4T‐1, PhO4T‐2, and PhO4T‐3) is constructed as a valuable platform for exploring the impact of the end group engineering on optoelectronic properties, intermolecular packing behaviors, and device performance. As a result, a high power conversion efficiency of 13.76% is achieved for PhO4T‐3 based OSCs, which is much higher than those of the PhO4T‐1 and PhO4T‐2‐based devices. Compared with several representative FREAs, PhO4T‐3 possesses the highest figure‐of‐merit value of 133.45 based on a cost‐efficiency evaluation. This work demonstrates that the simple‐structured NREAs‐II are promising candidates for low‐cost and high‐performance OSCs.

High‐Performance All‐Small‐Molecule Organic Solar Cells Enabled by Regio‐Isomerization of Noncovalently Conformational Locks

“…In particular, NoCLs have been employed to construct low‐cost and high‐performance nonfused‐ring electron acceptors for OSCs, which exhibited exciting PCE over 15% and high figure‐of‐merit value. [ 32–41 ] However, the application of NoCLs in designing SMDs have been rarely investigated, affording efficiencies of only ≈10%. [ 42,43 ]…”

“…In particular, NoCLs have been employed to construct low-cost and high-performance nonfused-ring electron acceptors for OSCs, which exhibited exciting PCE over 15% and high figure-of-merit value. [32][33][34][35][36][37][38][39][40][41] However, the application of NoCLs in designing SMDs have been rarely investigated, affording efficiencies of only ≈10%. [42,43] Besides, the isomerization strategy has been intensely employed to explore highly efficient materials for OSCs.…”

Unfused Acceptors Matching π‐Bridge Blocks with Proper Frameworks Enable Over 12% As‐Cast Organic Solar Cells

“…For this reason, unfused-ring acceptors (UFAs) have thus been proposed and now become a new hotspot in the field of OSCs. [19][20][21][22][23][24][25][26][27] Compared with rigid FREAs, UFAs adopt intramolecular noncovalent interactions) to ensure their coplanar backbones for high carrier mobility. [28][29][30][31][32][33][34][35] At present, the state-of-theart UFAs have pushed the maximum PCE to 15.44% after careful device optimization.…”

“…[32] Currently, most high-efficiency OSCs depend on device optimization including additives usage, spin-coating with hot solutions or on hot plates, and thermal annealing. [20][21][22]32,36] However, some additives may cause environmental pollution, while thermal annealing and hot spin-coating may increase energy consumption and process complexity. The exploring high-performance UFAs is highly demanding for as-cast OSCs, thus raising higher requirements for their structure design.For the development of UFAs, many up-and-coming building blocks have emerged.…”

“…For this reason, unfused-ring acceptors (UFAs) have thus been proposed and now become a new hotspot in the field of OSCs. [19][20][21][22][23][24][25][26][27] Compared with rigid FREAs, UFAs adopt intramolecular noncovalent interactions…”