A bi-continuous network structure of p-DTS(FBTTh2)(2)/EP-PDI via selective solvent vapor annealing
A bi-continuous network structure of p-DTS(FBTTh2)(2)/EP-PDI via selective solvent vapor annealing
复制标题
通过选择性溶剂蒸汽退火制备 p-DTS(FBTTh2)(2)/EP-PDI 双连续网络结构
DOI：
10.1039/c6tc03061k
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发表时间：
2016
影响因子：
6.4
通讯作者：
Yanchun Han
中科院分区：
文献类型：
--
作者：
Mingguang Li;Qiuju Liang;Qiaoqiao Zhao;Ke Zhou;Xinhong Yu;Zhiyuan Xie;Jiangang Liu;Yanchun Han
基于非富勒烯受体的小分子太阳能电池有效地分离和收集电荷的一个关键要求是形成10-20 nm的相互连接的相分离结构域。小分子施主7，7′-(4，4-bis(2-ethylhexyl)-4H-silolo[3，2-b:4，5-b′]dithiophene-2，6-diyl)bis(6-fluoro-4-(5′-hexyl-[2，2′-bithiophen]-5-yl)benzo[c][1，2，5]thiadiazole)(p-DTS(FBTTh2)2)和受体N，N′-bis(1-ethylpropyl)-perylene-3，4，9，10-tetracarboxylic二亚胺(EP-PDI)的相分离行为通过施主选择性溶剂蒸气退火来调节。差施主溶剂蒸气退火法(P-SVA)和热退火法(TA)。结果表明，经D-SVA处理后，功率转换效率(PCE)从不到0.2%显著提高到3.0%。相比之下，P-SVA(1.9%)和TA(1.8%)的PCE改善有限。不同后处理对PCE值改善的差异归因于相分离结构的形成和微晶尺寸的调节。在D-SVA处理过程中，p-DTS(FBTTh2)2形成纤维状晶体，而EP-PDI组分以小微晶的形式存在，从而形成所需的互联相分离结构。结果表明，适度的相分离形态伴随着中等尺寸的纯晶相，可以在不影响激子分离效率的情况下最大化载流子传输过程，从而在D-SVA下获得最终高达3.0%的最佳PCE值。对于P-SVA或TA处理，我们只观察到p-DTS(FBTTh2)2和EP-PDI组分的结晶度显著提高，导致显著的薄膜粗化，甚至不利于激子扩散和激子分离过程的大相分离。
A critical requirement of small molecule non-fullerene acceptor-based solar cells for efficient charge separation and collection is the formation of interconnected phase-separated domains of 10–20 nm. The phase-separation behavior of small molecule donor 7,7′-(4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b′]dithiophene-2,6-diyl)bis(6-fluoro-4-(5′-hexyl-[2,2′-bithiophen]-5-yl)benzo[c][1,2,5]thiadiazole) (p-DTS(FBTTh2)2) and acceptor N,N′-bis(1-ethylpropyl)-perylene-3,4,9,10-tetracarboxylic diimide (EP-PDI) was regulated by donor selective solvent vapor annealing (D-SVA), poor donor solvent vapor annealing (P-SVA) and thermal annealing (TA). It was found that the power conversion efficiency (PCE) was significantly improved from less than 0.2% up to 3.0% after D-SVA. In contrast, a limited improvement of PCE was obtained for P-SVA (1.9%) and TA (1.8%). The difference in the improvement of PCE values was attributed to the formation of a phase-separated structure and the regulation of crystallite sizes under different post treatments. The fibrous crystals of p-DTS(FBTTh2)2 were formed during D-SVA treatment while the EP-PDI component was in the form of small microcrystals, thus leading to the required interconnected phase-separated structure. As a consequence, the moderate phase-separated morphology accompanied by a pure crystalline phase with a medium size could maximize the carrier transport process without compromising exciton separation efficiency, and thus contributes to the final optimal PCE value of up to 3.0% under D-SVA. For P-SVA or TA treatment, we only observed a significant enhancement of the crystallinity of both p-DTS(FBTTh2)2 and EP-PDI components, leading to remarkable film coarsening, or even undesired large phase separation, which is detrimental to the exciton diffusion as well as exciton separation processes.