Gaspar Hugo, Parnell Andrew J, Pérez Gabriel E, Viana Júlio C, King Stephen M, Mendes Adélio, Pereira Luiz, Bernardo Gabriel
Institute for Polymers and Composites, University of Minho, 4800-058 Guimarães, Portugal.
LEPABE-Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
Nanomaterials (Basel). 2021 Dec 12;11(12):3367. doi: 10.3390/nano11123367.
The impact of several solvent processing additives (1-chloronaphthalene, methylnaphthalene, hexadecane, 1-phenyloctane, and p-anisaldehyde), 3% / in o-dichlorobenzene, on the performance and morphology of poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3‴-di(2-octyldodecyl)-2,2',5',22033,5″,2‴-quaterthiophen-5,5‴-diyl)] (PffBT4T-2OD):[6,6]-phenyl-C71-butyric acid methyl ester (PCBM)-based polymer solar cells was investigated. Some additives were shown to enhance the power conversion efficiency (PCE) by 6%, while others decreased the PCE by ~17-25% and a subset of the additives tested completely eliminated any power conversion efficiency and the operation as a photovoltaic device. Grazing-Incidence Wide Angle X-ray Scattering (GIWAXS) revealed a clear stepwise variation in the crystallinity of the systems when changing the additive between the two extreme situations of maximum PCE (1-chloronaphthalene) and null PCE (hexadecane). Small-Angle Neutron Scattering (SANS) revealed that the morphology of devices with PCE ~0% was composed of large domains with correlation lengths of ~30 nm, i.e., much larger than the typical exciton diffusion length (12 nm) in organic semiconductors. The graded variations in crystallinity and in nano-domain size observed between the two extreme situations (1-chloronaphthalene and hexadecane) were responsible for the observed graded variations in device performance.
研究了几种溶剂加工添加剂（1-氯萘、甲基萘、十六烷、1-苯基辛烷和对茴香醛）在邻二氯苯中3%的含量对聚[（5,6-二氟-2,1,3-苯并噻二唑-4,7-二基）-alt-（3,3‴-二（2-辛基十二烷基）-2,2',5',22033,5″,2‴-四噻吩-5,5‴-二基）]（PffBT4T-2OD）：[6,6]-苯基-C71-丁酸甲酯（PCBM）基聚合物太阳能电池性能和形态的影响。一些添加剂可使功率转换效率（PCE）提高约6%，而其他添加剂则使PCE降低约17 - 25%，并且所测试的一部分添加剂完全消除了任何功率转换效率以及作为光伏器件的运行。掠入射广角X射线散射（GIWAXS）表明，在最大PCE（1-氯萘）和零PCE（十六烷）这两种极端情况之间改变添加剂时，体系的结晶度存在明显的逐步变化。小角中子散射（SANS）表明，PCE约为0%的器件形态由相关长度约为30 nm的大区域组成，即远大于有机半导体中典型的激子扩散长度（约12 nm）。在两种极端情况（1-氯萘和十六烷）之间观察到的结晶度和纳米域尺寸的分级变化是器件性能分级变化的原因。
