Wouk Luana, Holakoei Soheila, Benatto Leandro, Pacheco Kaike Rosivan Maia, de Jesus Bassi Maiara, de Oliveira Camilla K B Q M, Bagnis Diego, Rocco Maria Luiza Miranda, Roman Lucimara Stolz
Department of Physics, Federal University of Paraná, Curitiba, 31531-990 Brazil.
CSEM Brasil, Belo Horizonte, 31035-536, Brazil.
J Phys Condens Matter. 2022 Mar 23;34(21). doi: 10.1088/1361-648X/ac4c12.
In this paper, the effect of a silafluorene derivative copolymer, the poly[2,7-(9,9-dioctyl-dibenzosilole)-alt-4,7-bis(thiophene-2-yl)benzo-2,1,3-thiadiazole] (PSiF-DBT) sensitized by a simpler homopolymer, the poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) were investigated in a bilayer and ternary blend configuration. The energy transfer between the polymers prior to electron transfer to the acceptors can be an efficient alternative to photocurrent improvement in photovoltaic devices. The interactions between the two donor polymer films were evaluated optically and morphologically with several experimental techniques and correlated to the photovoltaic performance. Improved photon to charge conversion was observed in the blend films at different device geometries-considering bilayer devices with fullerene and inverted flexible devices blade coated in air conditions with a non-fullerene small molecule acceptor. Resonant Auger spectroscopy using the core-hole clock method was employed to evaluate the ultrafast charge delocalization times of conjugated polymers in the low-femtosecond regime. Density functional theory and time-dependent DFT methods were used to help understand some experimental observations. The results show that the homopolymer can improve the absorption spectra and the nonradiative-energy transfer from MDMO-PPV to PSiF-DBT and act as a photosensitizer in the copolymer units. In addition, the PSiF-DBT blended with MDMO-PPV exhibits a more organized structure than the neat material resulting in better absorption stability of films kept under continuous illumination.
在本文中，研究了一种硅芴衍生物共聚物，即聚2,7-(9,9-二辛基-二苯并硅杂环戊二烯)-alt-4,7-双(噻吩-2-基)苯并-2,1,3-噻二唑，被一种更简单的均聚物，即聚2-甲氧基-5-(3',7'-二甲基辛氧基)-1,4-亚苯基亚乙烯基敏化后的双层和三元共混结构。在电子转移到受体之前，聚合物之间的能量转移可以成为提高光伏器件光电流的有效替代方法。通过几种实验技术对两种供体聚合物薄膜之间的相互作用进行了光学和形态学评估，并将其与光伏性能相关联。在不同器件几何结构的共混薄膜中观察到了光子到电荷转换的改善——考虑到具有富勒烯的双层器件以及在空气条件下用非富勒烯小分子受体刀片涂覆的倒置柔性器件。采用使用核孔时钟方法的共振俄歇光谱来评估共轭聚合物在低飞秒范围内的超快电荷离域时间。使用密度泛函理论和含时密度泛函理论方法来帮助理解一些实验观察结果。结果表明，均聚物可以改善吸收光谱以及从MDMO-PPV到PSiF-DBT的非辐射能量转移，并在共聚物单元中充当光敏剂。此外，与MDMO-PPV共混的PSiF-DBT比纯材料表现出更有序的结构，从而使在连续光照下保持的薄膜具有更好的吸收稳定性。
