Paek Sanghyun, Rub Malik Abdul, Choi Hyeju, Kosa Samia A, Alamry Khalid A, Cho Jin Woo, Gao Peng, Ko Jaejung, Asiri Abdullah M, Nazeeruddin Mohammad Khaja
Group for Molecular Engineering of Functional Materials, Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, Ecole polytechnique fédérale de Lausanne, CH-1951 Sion, Switzerland.
Center of Excellence for Advanced Materials Research (CEAMR), King Abdulaziz, University, Jeddah, Saudi Arabia.
Nanoscale. 2016 Mar 28;8(12):6335-40. doi: 10.1039/c5nr05697g.
We demonstrate for the first time an asymmetric squaraine-based low band-gap hole transporting material, which acted as both light harvesting and hole transporting layers in methylammonium lead triiodide perovskite solar cells. Opto-electrochemical characterization revealed extremely high molar extinction coefficients of the absorption bands in the low energy region and prominent space charge delocalization due to its electronically asymmetric nature. A suitable band alignment of the squaraine HOMO level with the valence band edge of the perovskite, and the conduction band of the TiO2 with LUMO of the perovskite allowed a cascade of hole extraction and electron injection, respectively. Red-shifted absorption was observed for both HTMs in thin films coated on the perovskite, and the optimized devices exhibited an impressive PCE of 14.7% under full sunlight illumination (100 mW cm(-2), AM1.5 G). The efficiency value is comparable to that of the devices using a state-of-the-art spiro-OMeTAD hole transport layer under similar conditions. Ambient stability after 300 h revealed that 88% of the initial efficiency remained for , and almost no change for , indicating that the devices had good long-term stability thus suggesting that the asymmetric squaraines have great potential as a dual-functional HTM for high performance perovskite solar cells.
我们首次展示了一种基于不对称方酸菁的低带隙空穴传输材料，它在甲脒铅三碘化物钙钛矿太阳能电池中同时充当光捕获层和空穴传输层。光电化学表征表明，由于其电子不对称性质，该材料在低能区域的吸收带具有极高的摩尔消光系数，并且具有显著的空间电荷离域。方酸菁的最高占据分子轨道（HOMO）能级与钙钛矿的价带边缘以及二氧化钛的导带与钙钛矿的最低未占据分子轨道（LUMO）之间的合适能带排列，分别允许空穴提取和电子注入的级联过程。在涂覆在钙钛矿上的薄膜中，两种空穴传输材料均观察到红移吸收，并且优化后的器件在全阳光照射（100 mW cm(-2)，AM1.5 G）下表现出令人印象深刻的14.7%的功率转换效率（PCE）。该效率值与在类似条件下使用最先进的螺环-OMeTAD空穴传输层的器件相当。300小时后的环境稳定性表明，[具体器件1]仍保留88%的初始效率，而[具体器件2]几乎没有变化，这表明这些器件具有良好的长期稳定性，因此表明不对称方酸菁作为高性能钙钛矿太阳能电池的双功能空穴传输材料具有巨大潜力。
