An all three-dimensional (3D)-printed flexible ZnO ultraviolet (UV) photodetector is demonstrated, where the 3D-printing method is used not only for the electrode and photosensitive material but also for creating a substrate. An ultraflat and flexible substrate capable of serving as the backbone layer is developed using a water-dissolvable polymer layer for surface planarization. A two-layered printing followed by surface treatment is demonstrated for the substrate preparation. As mechanical support but flexible, a thick and sparse thermoplastic polyurethane layer is printed. On its surface, a thin and dense poly(vinyl alcohol) (PVA) is then printed. A precise control of PVA reflow using a microwater droplet results in a flexible and extremely uniform substrate. A Cu-Ag nanowire network is directly 3D printed on the flexible substrate for the conducting layer, followed by ZnO for the photosensitive material. Unlike the planar two-dimensional printing that provides thin films, 3D printing allows the electrode to have a step height, which can be made like a dam to accommodate a thick film of ZnO. Photosensitivity as a function of various ZnO thickness values was investigated to establish an optimal thickness for UV response. The device was also tested in natural sunlight along with stability and reliability.

中文翻译：

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超薄基板上的所有3D打印的柔性ZnO UV光电探测器。

演示了全三维（3D）打印的柔性ZnO紫外（UV）光电探测器，其中3D打印方法不仅用于电极和光敏材料，而且用于创建基板。使用可溶于水的聚合物层对表面进行平坦化处理，从而开发出能够用作主干层的超平柔性基板。演示了用于基材制备的两层印刷，然后进行表面处理。作为机械支撑但有弹性，印刷了厚而稀疏的热塑性聚氨酯层。然后在其表面上印刷稀薄的聚乙烯醇（PVA）。使用微水滴对PVA回流进行精确控制可产生柔性且极其均匀的基材。将Cu-Ag纳米线网络直接3D打印在用于导电层的柔性基板上，然后将ZnO用于感光材料。与提供薄膜的平面二维打印不同，3D打印允许电极具有台阶高度，可以像坝一样将其制成以容纳ZnO的厚膜。研究了作为各种ZnO厚度值函数的光敏性，以建立紫外线响应的最佳厚度。该设备还经过了自然光以及稳定性和可靠性的测试。研究了作为各种ZnO厚度值函数的光敏性，以建立紫外线响应的最佳厚度。该设备还经过了自然光以及稳定性和可靠性的测试。研究了作为各种ZnO厚度值函数的光敏性，以建立紫外线响应的最佳厚度。该设备还经过了自然光以及稳定性和可靠性的测试。