Recent Progress and Challenges toward Highly Stable Nonfullerene Acceptor‐Based Organic Solar Cells

Abstract

Organic solar cells (OSCs) based on nonfullerene acceptors (NFAs) have made significant breakthrough in their device performance, now achieving a power conversion efficiency of ≈18% for single junction devices, driven by the rapid development in their molecular design and device engineering in recent years. However, achieving long‐term stability remains a major challenge to overcome for their commercialization, due in large part to the current lack of understanding of their degradation mechanisms as well as the design rules for enhancing their stability. In this review, the recent progress in understanding the degradation mechanisms and enhancing the stability of high performance NFA‐based OSCs is a specific focus. First, an overview of the recent advances in the molecular design and device engineering of several classes of high performance NFA‐based OSCs for various targeted applications is provided, before presenting a critical review of the different degradation mechanisms identified through photochemical‐, photo‐, and morphological degradation pathways. Potential strategies to address these degradation mechanisms for further stability enhancement, from molecular design, interfacial engineering, and morphology control perspectives, are also discussed. Finally, an outlook is given highlighting the remaining key challenges toward achieving the long‐term stability of NFA‐OSCs.

Comparing Donor- and Acceptor-Originated Exciton Dynamics in Non-Fullerene Acceptor Blend Polymeric Systems

“…The chemical names and structures of the abovementioned fluorinated NFA and polymeric materials are presented in Figure S1 in the Supplementary Materials section. NFA fluorination has triggered intense re-search activity to achieve higher PCE, demonstrated by the graphical trend of the "Best Research-Cell Efficiency Chart" [11] and insightful reviews [12,13]. Further advancements besides chemical tailoring include the use of ternary BHJ systems [14][15][16], in which multiple NFA components are blended together to form an active layer for single junction photovoltaic cells, and the use of tandem multijunction device structures [17].…”

Roles and Impacts of Ancillary Materials for Multi‐Component Blend Organic Photovoltaics towards High Efficiency and Stability

“…Although OPVs achieved remarkable growth over the past decades, they still do not meet the performance levels of already-commercialized silicon solar cells in terms of efficiency and stability. [8] Further, different deposition solvents are required according to the types and amounts of photoactive materials, which affect film morphology and thickness. [44] From this point of view, reliable and reproducible research in the field of OPVs is recommended to achieve commercialization.…”

“…[1,2] Organic photovoltaics (OPVs) are emerging as a next-generation photovoltaics (PVs) technology with great potential for scalable, [3][4][5] portable, [6] and transparent applications. [7] The commercial realization of these applications neared with advances in material designs and film processing techniques, [8][9][10][11] and the power conversion efficiency (PCE) of OPV devices reached up to 18 %, a value comparable to those of inorganic solar cells. [10][11][12][13] The remarkable advances in OPVs have been primarily due to bulk heterojunction (BHJ) blend systems employing electron donor (D) and acceptor (A) materials, which promote charge separation at the D/A interface for efficient photocurrent generation.…”

Dodecacyclic‐Fused Electron Acceptors with Multiple Electron‐Deficient Units for Efficient Organic Solar Cells

“…[61] After exposing these devices at 80°C for 96 h in the glove box filling with dry nitrogen atmosphere, PCEs of both devices retained 80 % for PBDB-T : MS-4F-based devices and 82 % for PBDB-T : MS-4Clbased devices, respectively, inferring that PBDB-T : MS-4Cl blend film might possess slightly better thermal stability than PBDB-T : MS-4F blend film. [62] However, both devices were very unstable in air and only retained about 50 % of the initial efficiency in 3 h (Figure S10c), indicating that oxygen and water may play additional role in the degradation of OSCs. [63]…”