Caballero-Quintana Irving, Amargós-Reyes Olivia, Maldonado José-Luis, Nicasio-Collazo Juan, Romero-Borja Daniel, Barreiro-Argüelles Denisse, Molnár Gábor, Bousseksou Azzedine
Research Group of Optical Properties of Materials (GPOM), Centro de Investigaciones en Óptica, A.P. 1-948, 37150 León, Guanajuato, México.
Laboratorio de Fisicoquı́mica y Reactividad de Superficies (LaFReS), Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México (UNAM), CU, Coyoacán, 04510, Ciudad de México, México.
ACS Appl Mater Interfaces. 2020 Jul 1;12(26):29520-29527. doi: 10.1021/acsami.0c06048. Epub 2020 Jun 9.
In this work, scanning probe microscopies (SPMs) are used for the analysis of PBDB-T, ITIC, and PBDB-T:ITIC layers of solar cells (OSCs). Scanning tunneling microscopy (STM) images of PBDB-T reveal that thin films (<1 nm) tend to form worm-like pattern (amorphous type) domains with an average chain-to-chain distance of 950 pm; likewise, STM images of ITIC show that side arms form chain-like patterns. STM images of PBDB-T:ITIC blend suggest why PBDB-T domains could facilitate charge dissociation. Further, a strong interchain π-π interaction of the ITIC molecules could promote self-organization, and under the mutual interaction with the PBDB-T polymer, it could influence the pathway formation for electron transport. Moreover, when correlating electrostatic force microscopy (EFM) and photoconductive atomic force microscopy (pc-AFM), the blend morphology and its electrical/electronic properties are determined; the ideal domain size of PBDB-T:ITIC blend phases for maximizing the generated photocurrent is 15-35 nm. Furthermore, phase contrast and surface electric potential characteristics with Kelvin probe force microscopy (KPFM) are measured to examine additional details about the surface and potential changes due to the domain differences in the active layer. OSCs based on the nonfullerene PBDB-T:ITIC active layer reach an average power conversion efficiency (PCE) of 9.1% (best 9.2%).
在这项工作中，扫描探针显微镜（SPM）用于分析太阳能电池（OSC）的PBDB-T、ITIC和PBDB-T:ITIC层。PBDB-T的扫描隧道显微镜（STM）图像显示，薄膜（<1nm）倾向于形成蠕虫状图案（非晶型）畴，平均链间距离为950pm；同样，ITIC的STM图像表明侧臂形成链状图案。PBDB-T:ITIC共混物的STM图像揭示了PBDB-T畴促进电荷解离的原因。此外，ITIC分子之间强烈的链间π-π相互作用可促进自组装，并且在与PBDB-T聚合物的相互作用下，它可影响电子传输的路径形成。此外，当将静电力显微镜（EFM）和光导原子力显微镜（pc-AFM）关联起来时，可确定共混物的形态及其电学/电子性质；使产生的光电流最大化的PBDB-T:ITIC共混相的理想畴尺寸为15-35nm。此外，利用开尔文探针力显微镜（KPFM）测量相衬度和表面电势特性，以检查由于活性层中的畴差异而导致的表面和电势变化的更多细节。基于非富勒烯PBDB-T:ITIC活性层的OSC平均功率转换效率（PCE）达到9.1%（最佳值为9.2%）。
