文章信息/Info

Title:

Control of the Crystallization and Phase Separation in Sequential Blade Coated Organic Solar Cells

文章編號:

1674-3962(2022)03-0161-08

作者:

王藝林; 周科; 馬偉

（西安交通大學(xué)材料科學(xué)與工程學(xué)院 金屬強(qiáng)度國家重點(diǎn)實(shí)驗(yàn)室，陜西 西安 710049）

Author(s):

WANG Yilin; ZHOU Ke; MA Wei

（State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China）

關(guān)鍵詞:

有機(jī)太陽能電池; 順序刮涂; 形貌; 結(jié)晶; 垂直相分離; 大面積器件

Keywords:

organic solar cells; sequential blade coating; morphology; crystallization; vertical phase separation; large-area devices

分類號:

TM914.4;TN15;O631.4

DOI:

10.7502/j.issn.1674-3962.202202006

文獻(xiàn)標(biāo)志碼:

A

摘要:

活性層形貌對有機(jī)光伏器件性能有重要影響，在本體異質(zhì)結(jié)（BHJ）結(jié)構(gòu)中，活性層微觀形貌復(fù)雜，難以精確調(diào)控。相比之下，順序加工P-i-N結(jié)構(gòu)可以單獨(dú)加工給/受體，使得形貌調(diào)控更簡單易行。然而，目前順序加工形貌優(yōu)化的相關(guān)機(jī)理研究相對缺乏，不利于其在大面積器件中的應(yīng)用。基于此，采用順序刮涂制備了基于PM6/Y6體系的P-i-N結(jié)構(gòu)器件，并對其基于形貌優(yōu)化提高器件性能的機(jī)理進(jìn)行了研究。與BHJ結(jié)構(gòu)相比，順序刮涂薄膜從陽極到陰極形成了給體富集相/共混相/受體富集相的梯度分布結(jié)構(gòu)；同時(shí)，順序刮涂有效提升了給/受體的結(jié)晶性。梯度分布結(jié)構(gòu)和結(jié)晶性的協(xié)同優(yōu)化使得器件中的電荷遷移率更加平衡，載流子復(fù)合減少，電荷收集效率提高，因此獲得了最高15.84%的光電轉(zhuǎn)化效率（BHJ結(jié)構(gòu)15.16%）。更為重要的是，通過進(jìn)一步優(yōu)化大面積順序刮涂工藝，活性層形貌缺陷減少，從而有效降低了大面積器件效率損失。以上結(jié)果表明了順序刮涂策略在實(shí)現(xiàn)活性層形貌優(yōu)化和制備高效大面積器件方面的巨大潛力。

Abstract:

The bulk heterojunction (BHJ) morphology of organic solar cells (OSCs) is critically important for achieving high device performance. While the microstructure optimization in a single casting process is extremely complicated due to the coupling of crystallization and phase separation of the photoactive materials. By contrast, the sequential blade coated P-i-N structure of the donor and acceptor materials can lead to a more favorable morphology and nanostructure, which is an efficient method to circumvent the existing issue in single-solvent BHJ device fabrication. However, the underlying mechanism of morphology optimization in sequential blade coating process and how it impacts the device performance are still mysterious, which limit the application of this method in the manufacture of high-efficiency large-area devices. Herein, the inverted P-i-N device based on PM6/Y6 system was fabricated in ambient environment and the mechanism of improved device performance based on morphology optimization was studied in detail. Compared to the single-solvent method, sequential blade coating strategy successfully controlled the crystallization and phase separation of active layer, and the gradient distribution of donor-rich phase/mixing phase/acceptor-rich phase from anode to cathode was formed. More importantly, this strategy eliminated the interaction between donor and acceptor molecules, thus effectively enhanced the crystallinity of donor and acceptor. Based on the simultaneous optimization of vertical phase separation and crystallinity, more balanced hole/electron mobility and reduced carrier recombination were achieved, leading to the highest power conversion efficiency (PCE) of 15.84% in P-i-N device (15.16% for the BHJ control device). It is worth noting that by further optimizing the large-area sequential blade coating process, the morphologic defects of large-area active layer were effectively reduced, resulting in higher PCE of large-area P-i-N device. This indicates the sequential blade coating strategy provides an important guideline for the optimization of large-area fabrication in OSCs.