Highly-Effi cient, Flexible Piezoelectric PZT Thin Film Nanogenerator on Plastic Substrates
Highly-Effi cient, Flexible Piezoelectric PZT Thin Film Nanogenerator on Plastic Substrates
复制标题
DOI：
10.1002/adma.201305659
复制
发表时间：
2014-04-01
影响因子：
29.4
通讯作者：
Lee, Keon Jae
中科院分区：
文献类型：
--
作者：
Park, Kwi-Il;Son, Jung Hwan;Lee, Keon Jae
DOI：10.1002/adma。 201305659 聚合物基质中的碳，然后夹在顶部和底部涂有电极的塑料基材之间。然而，尽管它们作为柔性能量收集器具有巨大的潜力，但这些压电NG在用于操作有用的毫瓦级消费电子产品时仍然表现出不足的输出性能，因为它们的压电特性较低[14-16]，或者由于使用两个夹层塑料基板或厚的压电聚合物层而导致能量转换率较低。 [17-19] 为了提高NGs的转换效率，包括我们小组在内的研究人员已经使用软光刻转移技术在塑料基板上展示了固有的高压钙钛矿薄膜，从而在柔性基板上实现了高质量的薄膜材料。[20-23]在这些尝试中，尽管在周期性机械过程中实现了高度柔性和敏感的薄膜NGs（∼7 mW·cm−3） [20]在此，我们通过激光剥离（LLO）工艺展示了柔性基板上的大面积 PZT 薄膜，并制造了薄膜 NG，以实现高效、轻量化和柔性的压电能量收集器件。 LLO转移工艺是一种广泛商业化的技术，可用于从垂直发光二极管（LED）的蓝宝石衬底上分离氮化镓薄膜。[24-26]我们采用这种技术将高质量压电薄膜从块状蓝宝石衬底转移到塑料衬底上。通过对透明蓝宝石背面进行 XeCl 准分子激光照射，PZT 薄膜的整个区域可以转移到柔性聚对苯二甲酸乙二醇酯 (PET) 基板上，而不会造成结构损坏。单个薄塑料基板上的最终 PZT 薄膜 NG 通过轻微的机械变形实现了约 200 V 和约 150 µA·cm− 2 的高输出性能。大面积 NG（3.5 cm× 3.5 cm）产生的短路电流高达~ 8 µA，并且可以轻松地让 100 多个商用蓝色 LED 阵列在人类手指轻微弯曲的情况下工作。图 1a 显示了使用 LLO 工艺制造柔性大面积 PZT 薄膜 NG 的示意图。采用传统的溶胶-凝胶法在双面抛光的蓝宝石基板（Hi-Solar Co.，厚度430 µm）上沉积了优异的压电PZT薄膜。将市售的 0.4 M PZT 化学溶液（MEMS Solution Co.，Zr/Ti 的组成比为 52/48，其中含有 10 mol% 过量的 PbO）以 2500 rpm 的转速旋涂 20 秒，然后使用快速热退火 (RTA) 在 450 C 下在空气中热解 10 分钟以去除有机物。重复这些沉积和热解过程，直到形成 2 µm 厚的 PZTEnergy 能量采集器，它可以将振动和机械能源转换为电能，是非常有前途的工具，可以在孤立的、难以接近的或室内环境甚至人体条件下实现可持续能源生成。 [1, 2] 特别是，由于单个薄塑料基板上的灵活且轻便的能量采集装置可以从极其微小的运动中采集能量 将风、水流、心跳、横膈膜活动和呼吸运动等转化为电信号，[3-5]它不仅可以实现自供电的柔性电子系统[3, 4]，还可以实现植入式生物医学设备的永久电源，例如心脏转速计、[6]起搏器、[7]和深部脑刺激器。[8 ...
DOI: 10.1002/adma. 201305659 carbons in a polymer matrix which was then sandwiched between the top and bottom electrode-coated plastic substrates. However, despite their remarkable potential for use as flexible energy harvesters, these above piezoelectric NGs still show either insufficient output performance when used to operate useful mW-level consumer electronics due to their low piezoelectric properties [14–16] or low energy conversion rates owing to the utilization of two sandwiched plastic substrates or thick piezoelectric polymer layers.[17–19] In order to enhance the conversion efficiency of NGs, researchers, including our group, have demonstrated an inherently high piezoelectric perovskite thin film on a plastic substrate using a soft-lithographic transfer technique, enabling high-quality thin film materials on a flexible substrate.[20–23] In those attempts, although highly flexible and sensitive thin film NGs (∼ 7 mW· cm− 3) were achieved during periodic mechanical deformations, there are still limitations of low output performance (∼ 1.0 V and∼ 26 nA) and complicated process for industrial applications.[20] Herein, we demonstrated a large-area PZT thin film on flexible substrates via a laser lift-off (LLO) process and fabricated a thin film NG to realize highly-efficient, lightweight, and flexible piezoelectric energy harvesting devices. The LLO transfer process is a widely commercialized technique that can be used to detach gallium nitride film from a sapphire substrate for a vertical light-emitting diode (LED).[24–26] We adopt this technique to transfer a high-quality piezoelectric thin film from bulk sapphire substrates to plastic substrates. By XeCl excimer laser irradiation on the backside of the transparent sapphire, the entire area of the PZT thin films can be transferred onto a flexible polyethylene terephthalate (PET) substrate without causing structural damage. The final PZT thin film NG on a single thin plastic substrate converted a high-output performance of∼ 200 V and∼ 150 µA· cm− 2 from the slight mechanical deformations. The short-circuit current generated from a large-area NG (3.5 cm× 3.5 cm) reached up to∼ 8 µA and readily allowed more than 100 commercial blue LED arrays to operate during slight bending motions by human fingers. Figure 1a shows the schematic illustration of the fabrication steps of flexible and large-area PZT thin film NG using the LLO process. An excellent piezoelectric PZT thin film was deposited on a double-side polished sapphire substrate (Hi-Solar Co., 430 µm in thickness) by a conventional sol-gel method. A commercially available 0.4 M PZT chemical solution (MEMS solution Co., a 52/48 composition ratio of Zr/Ti with 10 mol% excess PbO) was spin-coated at 2500 rpm for 20 s and subsequently pyrolyzed in air using rapid thermal annealing (RTA) at 450 C for 10 min to remove the organics. These deposition and pyrolysis processes were repeated until a 2 µm thick PZTEnergy harvesters which can convert electrical energy from vibrational and mechanical energy sources are very promising tools to realize the sustainable energy generation in isolated, inaccessible or indoor environments and even in human body conditions.[1, 2] In particular, since the flexible and lightweight energy harvesting device on a single thin plastic substrate can scavenge from the extremely tiny movements such as wind, water flows, heartbeats, diaphragm activities, and respiration movements into electric signals,[3–5] it can realize not only selfpowered flexible electronic systems [3, 4] but also permanent power sources for implantable biomedical devices such as cardiac-tachometers,[6] pacemakers,[7] and deep brain stimulators.[8 …