Kawashima Kazuhiro, Okamoto Yuji, Annayev Orazmuhammet, Toyokura Nobuo, Takahashi Ryota, Lippmaa Mikk, Itaka Kenji, Suzuki Yoshikazu, Matsuki Nobuyuki, Koinuma Hideomi
Fundamental Research Department, Comet Co. Ltd, Tsukuba, Japan.
Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Japan.
Sci Technol Adv Mater. 2017 Apr 28;18(1):307-315. doi: 10.1080/14686996.2017.1314172. eCollection 2017.
As an extension of combinatorial molecular layer epitaxy via ablation of perovskite oxides by a pulsed excimer laser, we have developed a laser molecular beam epitaxy (MBE) system for parallel integration of nano-scaled thin films of organic-inorganic hybrid materials. A pulsed infrared (IR) semiconductor laser was adopted for thermal evaporation of organic halide (A-site: CHNHI) and inorganic halide (B-site: PbI) powder targets to deposit repeated A/B bilayer films where the thickness of each layer was controlled on molecular layer scale by programming the evaporation IR laser pulse number, length, or power. The layer thickness was monitored with an quartz crystal microbalance and calibrated against stylus profilometer measurements. A computer-controlled movable mask system enabled the deposition of combinatorial thin film libraries, where each library contains a vertically homogeneous film with spatially programmable A- and B-layer thicknesses. On the composition gradient film, a hole transport Spiro-OMeTAD layer was spin-coated and dried followed by the vacuum evaporation of Ag electrodes to form the solar cell. The preliminary cell performance was evaluated by measuring - characteristics at seven different positions on the 12.5 mm × 12.5 mm combinatorial library sample with seven 2 mm × 4 mm slits under a solar simulator irradiation. The combinatorial solar cell library clearly demonstrated that the energy conversion efficiency sharply changes from nearly zero to 10.2% as a function of the illumination area in the library. The exploration of deposition parameters for obtaining optimum performance could thus be greatly accelerated. Since the thickness ratio of PbI and CHNHI can be freely chosen along the shadow mask movement, these experiments show the potential of this system for high-throughput screening of optimum chemical composition in the binary film library and application to halide perovskite solar cell.
作为通过脉冲准分子激光烧蚀钙钛矿氧化物实现的组合分子层外延的扩展，我们开发了一种用于有机-无机杂化材料纳米级薄膜并行集成的激光分子束外延（MBE）系统。采用脉冲红外（IR）半导体激光器对有机卤化物（A位：CHNHI）和无机卤化物（B位：PbI）粉末靶材进行热蒸发，以沉积重复的A/B双层膜，其中每层的厚度通过对蒸发红外激光脉冲数、长度或功率进行编程，在分子层尺度上进行控制。用石英晶体微天平监测层厚度，并根据触针轮廓仪测量进行校准。计算机控制的可移动掩膜系统能够沉积组合薄膜库，其中每个库包含具有空间可编程A层和B层厚度的垂直均匀薄膜。在组成梯度膜上，旋涂并干燥空穴传输Spiro-OMeTAD层，然后真空蒸发Ag电极以形成太阳能电池。通过在太阳模拟器照射下，在具有七个2mm×4mm狭缝的12.5mm×12.5mm组合库样品上的七个不同位置测量-特性，对初步电池性能进行评估。组合太阳能电池库清楚地表明，能量转换效率作为库中光照面积的函数，从几乎为零急剧变化到10.2%。因此，可以大大加速获得最佳性能的沉积参数的探索。由于PbI和CHNHI的厚度比可以沿着荫罩移动自由选择，这些实验展示了该系统在二元膜库中高通量筛选最佳化学成分以及应用于卤化物钙钛矿太阳能电池方面的潜力。
