Benzotriazole‐Based Nonfused Ring Acceptors for Efficient and Thermally Stable Organic Solar Cells

Abstract

Nonfused ring acceptors (NFRAs) have attracted significant attention for nonfullerene organic solar cells (OSCs) owing to their chemical tunability and facile synthesis. In this study, a benzotriazole-based NFRA with chlorinated end groups (Triazole-4Cl) is developed to realize highly efficient and thermally stable NFRA-based OSCs; an analogous NFRA with nonchlorinated end groups (Triazole-H) is synthesized for comparison. Triazole-4Cl film exhibits the high-order packing structure and the near-infrared absorption capability, which are advantageous in charge transport and light harvesting of the resulting OSCs. In particular, the strong crystalline behavior of Triazole-4Cl results in enhanced self-aggregation, leading to high charge carrier mobility. Owing to these properties, a PBDB-T (polymer donor):Triazole-4Cl OSC demonstrates a high short-circuit current, fill factor, and power conversion efficiency (PCE = 10.46%), outperforming a PBDB-T:Triazole-H OSC (PCE = 7.65%). In addition, the thermal stability of a PBDB-T:Triazole-4Cl OSC at an elevated temperature of 120 °C exceeds that of a PBDB-T:Triazole-H OSC. This is mainly attributed to the significantly higher cold crystallization temperature of Triazole-4Cl (205.9 °C). This work provides useful guidelines for the design of NFRAs to achieve efficient and thermally stable NFRA-based OSCs.

Diffusion‐Limited Accepter Alloy Enables Highly Efficient and Stable Organic Solar Cells

“…[1][2][3][4][5][6][7] The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.202214392. of its initial PCE after thermal treatment at 120 °C for 116 h. [26] The utilization of an extra UV crosslinker was also verified to be a feasible method for confining the segment relations of the photovoltaic materials to lock BHJ morphology upon thermal treatment. [27][28][29] Moreover, due to the intrinsic characteristic of high-temperature resistance, insulating polymeric matrices, i.e., poly(aryl ether) and polyacenaphthylene, were introduced to elevate thermal stability in device.…”

“…To minimize the trade‐off between device efficiency and stability in OSCs, great efforts have been devoted to investigating effective strategies that can suppress the diffusion‐enabled demixing of the morphology under thermal stress. For example, the non‐fullerene SMAs with weak crystallinity, i.e., feature‐less thermally phase transition, retained 75% of its initial PCE after thermal treatment at 120 °C for 116 h. [ 26 ] The utilization of an extra UV crosslinker was also verified to be a feasible method for confining the segment relations of the photovoltaic materials to lock BHJ morphology upon thermal treatment. [ 27–29 ] Moreover, due to the intrinsic characteristic of high‐temperature resistance, insulating polymeric matrices, i.e., poly(aryl ether) and polyacenaphthylene, were introduced to elevate thermal stability in device.…”

Tethered Small‐Molecule Acceptors Simultaneously Enhance the Efficiency and Stability of Polymer Solar Cells

“…[54,55] In this way, the miscibility of different blends can be identified via their χ value. [27,56] It has been disclosed that the PM6:Y6 blend features a hypo-miscibility, typically below the percolation threshold. [30] This means that the morphologies of PM6: Y6 blend is neither thermodynamically or sufficiently kinetically stabilized against over-purification and possibly crystallization (Figure 6c,e), particularly at elevated temperatures where diffusion proceeds more readily.…”

Research Progress of Thermal Failure Mechanism and Ternary Blending to Improve Thermal Stability of Organic Solar Cells

“…Copyright 2019, Cell Press 马伟等 [51] 在之前的报道中证明了 T cc 与 PffBT4T-2OD: ITIC 共混物的相大小和相纯度的相关性(图 2c), 当温度 在 T cc 以下时, 聚合物复杂的链段缠结阻碍了 NFA 的重 排, 因此共混膜形貌能保持稳定. Kim 等 [52] 的研究也表 明 PBDB-T:Triazole-Cl 相较于 PBDB-T:Triazole-H 在 120 ℃加热下更好的热稳定性是由于 Triazole-Cl 的 T cc 更高, 抑制了分子链段的运动, 从而改善了热应力下的 相偏析.…”