低温制备基于ZnO纳米线阵列为电子传输层的柔性PbS胶体量子点太阳能电池的研究

发布时间：2018-10-05 18:17

【摘要】：PbS胶体量子点在量子尺寸效应下的带隙可调,低温液相合成,室温下旋涂成膜,多激子效应,PbS胶体量子点太阳能电池在低成本的柔性薄膜光伏研究领域引起了广泛的关注。目前,柔性器件以平面异质结构为主,在平面异质结结构器件中,吸收层厚度不足限制光生电流的提高,使得器件效率较低。以无机纳米粒子堆积的薄膜为电子传输层时,易产生裂痕导致器件性能的损失。解决这些问题是进一步发展柔性器件的重要方向。为了解决上述问题,我们以ZnO纳米线阵列为电子传输层构建了三维异质结结构PbS胶体量子点太阳能电池,三维结构有利于载流子的定向输运和收集,而且光生载流子的方向与光吸收方向正交,大大地提高了光生电流密度和器件转换效率。在提高器件抗弯折性方面,三维的间隙结构可以有效的释放弯折应力,提高器件的抗弯折性能,对于未来可穿戴柔性太阳能电池的应用非常重要。我们通过在室温下旋涂预先合成的ZnO纳米粒子前驱液作为晶种层,再通过水热合成的方法低温制备三维结构ZnO纳米线阵列作为PbS胶体量子点太阳能电池电子传输层。我们利用该低温方法在柔性衬底上生长了形貌和长度可控生长的ZnO纳米线阵列,其具有高结晶质量,低缺陷态密度,高透光性等优越性能。我们以ZnO纳米粒子和ZnO纳米阵列作为电子传输层在柔性衬底上构建了PbS胶体量子点太阳能电池。研究发现,三维器件具有更高的短路电流,但损失了一部分开路电压,整体的效率与平面结构器件的效率相当。在弯曲性测试中,在160°弯曲角度下,对比两种柔性器件的抗弯折性能,三维器件各参数都保持较高的性能,而平面器件的短路电流和填充因子下降明显,最终三维器件的效率变化高出平面器件的16%。我们对比弯折后器件各部分形貌的变化,发现弯折后只有平面的ZnO纳米粒子薄膜出现明显的裂痕,这是由于平整薄膜不能有效释放应力,导致器件的短路电流和填充因子下降明显。ZnO纳米线阵列因其间隙结构能有效释放弯折应力,从而使得器件各参数在弯折后均未出现明显降低,抗弯折性能得到了明显的提高,为其应用于其他柔性器件提供了参考和方向。
[Abstract]:The tunable band gap of PbS colloidal quantum dots in quantum size effect, low temperature liquid phase synthesis, spin-coating film at room temperature and multi-exciton effect have attracted wide attention in the field of low-cost flexible thin film photovoltaic research. At present, the flexible devices are mainly planar heterostructure. In the planar heterojunction devices, the thickness of absorption layer is insufficient to limit the increase of photogenerated current, which makes the device low efficiency. When the film deposited by inorganic nanoparticles is used as the electron transport layer, it is easy to produce cracks and lead to the loss of device performance. Solving these problems is an important direction for the further development of flexible devices. In order to solve the above problems, we have constructed a three-dimensional heterojunction PbS colloidal quantum dot solar cell with ZnO nanowire array as the electron transport layer. The three-dimensional structure is conducive to the directional transport and collection of carriers. Moreover, the direction of photogenerated carriers is orthogonal to the direction of optical absorption, which greatly improves the photogenerated current density and the conversion efficiency of the devices. In the aspect of improving the bending resistance of the devices, the three-dimensional gap structure can effectively release the bending stress and improve the bending performance of the devices, which is very important for the application of wearable flexible solar cells in the future. Three-dimensional ZnO nanowire arrays were prepared by spin-coating pre-synthesized precursor of ZnO nanoparticles at room temperature as seed layer and hydrothermal synthesis at low temperature as the electron transport layer of PbS colloidal quantum dots solar cells. We have grown ZnO nanowire arrays with controlled morphology and length on flexible substrates by using the low temperature method. The nanowires have excellent properties such as high crystallization quality, low defect density of states, high transmittance and so on. We have constructed PbS colloidal quantum dot solar cells on flexible substrates using ZnO nanoparticles and ZnO nanoarrays as electron transport layers. It is found that the 3D device has a higher short-circuit current, but loses part of the open-circuit voltage, and the overall efficiency is equivalent to that of the planar device. In the bending test, compared with the flexural properties of the two flexible devices at 160 掳bending angle, each parameter of the 3D device keeps higher performance, while the short-circuit current and the filling factor of the planar device decrease obviously. In the end, the efficiency of three-dimensional devices is higher than that of planar devices. By comparing the morphologies of various parts of the device after bending, we find that only the planar ZnO nanoparticles film has obvious cracks after bending, which is due to the fact that the flat film can not release the stress effectively. The short circuit current and filling factor of the device decrease obviously. The gap structure of ZnO nanowire array can effectively release the bending stress, so that the parameters of the device are not obviously reduced after bending, and the bending performance is obviously improved. It provides reference and direction for its application in other flexible devices.
【学位授予单位】：东北师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM914.4

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