School of Integrative Engineering, Chung-Ang University, 84 Heukseok-Ro, Dongjak-gu, Seoul 06974, Republic of Korea.
Nanoscale. 2018 Mar 8;10(10):4708-4717. doi: 10.1039/c7nr08797g.
Herein, solvent-treated bandgap-tunable covalent organic nanosheets (CONs) were prepared via the Stille cross-coupling reaction. These materials are considered useful as interlayers in photovoltaic devices upon the alignment of energy levels between other components. Among various types of solar cells, according to the organic-interlayer study, inverted planar perovskite solar cells (PSCs) are mostly demanded to effectively transport and collect charge carriers due to their high performance. At first, the C-V analysis proved the energy levels of the frontier orbitals for CON-10 and CON-16 nanosheets; this verified the suitability of these nanosheets as hole transport layers (HTLs) with the PEDOT:PSS upon casting both films from DMSO. It became evident, however, that the hole transport property of the PEDOT:PSS on the CON-16 layer was unfavorable with the increasing UPS-proven hole injection barrier. In addition, both CONs induced a rough surface morphology; however, CON-10 showed a relatively smooth surface as compared to CON-16 based on the Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) profiles; furthermore, their surface properties influenced both the PEDOT:PSS layers and the perovskite layers. Especially, the XRD profiles presented an enhanced crystallinity of the perovskite layers with CON-10. All these aspects indicate that CON-10 is a more effective HTL material, and several versions of perovskite solar cells (PSCs) have been fabricated with/without CON-10 and CON-16 together with the PEDOT:PSS to determine the more-HTL-suitable CON. As a result, the power conversion efficiencies (PCEs) of the optimized devices with CON-10 exhibited a value of 10.2%, which represented a 1% increase over those of the reference devices without the CONs and was 4% higher than that of the CON-16 devices. Moreover, the devices with CON-10 were further optimized with TiO using Al electrodes, leading to a PCE increase of these devices that became slightly higher than the PCEs of the device with CON-10 and without TiO. This tendency was supported by photoluminescence (PL) spectroscopy, photocurrent density (J), and space-charge-limited current (SCLC) mobility results.
本文通过 Stille 交叉偶联反应制备了溶剂处理的带隙可调共价有机纳米片（CONs）。这些材料被认为是有用的层间材料，可以在其他组件的能级对齐后用于光伏器件。在各种类型的太阳能电池中，根据有机层间的研究，由于性能较高，倒置平面钙钛矿太阳能电池（PSCs）最需要有效地传输和收集电荷载流子。首先，C-V 分析证明了 CON-10 和 CON-16 纳米片的前沿轨道能级；这证明了这些纳米片适合作为空穴传输层（HTLs），与从 DMSO 浇铸两种薄膜的 PEDOT:PSS 一起使用。然而，随着 UPS 证明的空穴注入势垒的增加，PEDOT:PSS 在 CON-16 层上的空穴传输性能变得不利。此外，两种 CON 都诱导出粗糙的表面形貌；然而，基于扫描电子显微镜（SEM）和原子力显微镜（AFM）形貌，CON-10 显示出相对光滑的表面，而 CON-16 则显示出粗糙的表面；此外，它们的表面特性影响 PEDOT:PSS 层和钙钛矿层。特别是，XRD 图谱显示出 CON-10 具有增强的钙钛矿层结晶度。所有这些方面都表明 CON-10 是一种更有效的 HTL 材料，并且已经制备了几种版本的钙钛矿太阳能电池（PSCs），其中包含和不包含 CON-10 和 CON-16 以及 PEDOT:PSS，以确定更适合 HTL 的 CON。结果，具有 CON-10 的优化器件的功率转换效率（PCE）表现出 10.2%的值，比没有 CON 的参考器件提高了 1%，比 CON-16 器件高 4%。此外，使用 Al 电极对具有 CON-10 的器件进行了进一步优化，导致这些器件的 PCE 略有增加，略高于具有 CON-10 和没有 TiO 的器件的 PCE。这种趋势得到了光致发光（PL）光谱、光电流密度（J）和空间电荷限制电流（SCLC）迁移率结果的支持。
