Unraveling complex performance-limiting factors of brominated ITIC derivative: PM6 organic solar cells by using time-resolved measurements
Unraveling complex performance-limiting factors of brominated ITIC derivative: PM6 organic solar cells by using time-resolved measurements
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DOI：
10.1038/s41428-022-00704-1
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发表时间：
2022-09
期刊：
影响因子：
2.8
通讯作者：
Shaoxian Li;Ryosuke Nishikubo;Tatsuho Wada;T. Umeyama;H. Imahori;A. Saeki
中科院分区：
文献类型：
--
作者：
Shaoxian Li;Ryosuke Nishikubo;Tatsuho Wada;T. Umeyama;H. Imahori;A. Saeki
由聚合物和非富勒烯受体（NFA）组成的有机太阳能电池（OSC）在功率转换效率（PCE）方面取得了显着的改善，但许多影响因素的作用仍然没有完全了解。电荷载流子迁移率通常被认为是NFA-OSC性能的积极因素，但这种说法往往与实验结果相矛盾。在这方面，在末端IC基团的β、γ和δ位置溴化的基于引达省二噻吩并[3，2-B]噻吩的NFA（ITIC）适合于性能限制因素的比较研究。在这项工作中，我们评估了这些ITIC（β，γ，δ）：PM 6体异质结OSC中的载流子动力学通过使用同时飞行时间（TOF）-时间分辨微波电导率（TRMC）和光诱导电荷提取线性增加电压（photo-CELIV）技术。所测得的这些OSC的PCE的顺序为ITIC-γ：PM 6（9.3%）> ITIC-β：PM 6（8.5%）> ITIC：PM 6（7.5%）> ITIC-δ：PM 6（2.3%）。TOF-TRMC/photo-CELIV结果显示，尽管具有最高的PCE，ITIC-γ：PM 6显示出低的电子和空穴迁移率，而其迁移率弛豫特性在OSC中是中等的。相比之下，ITIC-γ：PM 6表现出最小的双分子复合系数。最后，15个参数（移动性等）进行了线性回归分析，这提供了一个定量的了解复杂的PCE的NFA OSC的控制因素。
Organic solar cells (OSCs) composed of a polymer and nonfullerene acceptor (NFA) have achieved dramatic improvements in power conversion efficiency (PCE), while the roles of many contributing factors are still not fully understood. Charge carrier mobility is conventionally considered a positive factor for NFA-OSC performance, yet this statement is often contradicted by experimental results. In this regard, indacenodithieno[3,2-b]thiophene-based NFAs (ITIC) brominated at theβ,γ, andδpositions of the terminal IC groups are suitable for a comparative study of the performance-limiting factors. In this work, we evaluated the charge carrier dynamics in these ITIC (β,γ,δ):PM6 bulk heterojunction OSCs by using simultaneous time-of-flight (TOF)-time-resolved microwave conductivity (TRMC) and photoinduced charge extraction by linearly increasing voltage (photo-CELIV) techniques. The measured PCEs of these OSCs decreased in the order ITIC-γ:PM6 (9.3%) > ITIC-β:PM6 (8.5%) > ITIC:PM6 (7.5%) > ITIC-δ:PM6 (2.3%). The TOF-TRMC/photo-CELIV results revealed that despite having the highest PCE, ITIC-γ:PM6 showed both low electron and hole mobilities, while its mobility relaxation characteristics were moderate among those of the OSCs. In contrast, ITIC-γ:PM6 showed the smallest bimolecular recombination coefficient. Finally, fifteen parameters (mobility, etc.) were subjected to a linear regression analysis, which provided a quantitative understanding of the complex PCE-governing factors for NFA OSCs.