Nanostructured hybrid materials (NHMs) are promising candidates to improve the performance of several materials in different applications. In the case of optoelectronic technologies, the ability to tune the optical absorption of such NHMs is an appealing feature. Along with the capacity to transform the absorbed light into charge carriers (CC), and their consequently efficient transport to the different electrodes. In this regard, NHM based on graphene-like structures and semiconductor QDs are appealing candidates, assuming the NHMs retain the light absorption and CC photogeneration properties of semiconductor QDs, and the excellent CC transport properties displayed by graphene-like materials. In the current work a solution-processed NHM using PbS quantum dots (QDs) and graphene oxide (GO) was fabricated in a layer-by-layer configuration by dip-coating. Afterwards, these NHMs were reduced by thermal or chemical methods. Reduction process had a direct impact on the final optoelectronic properties displayed by the NHMs. All reduced samples displayed a decrement in their resistivity, particularly the sample chemically reduced, displaying a 107fold decrease; mainly attributed to N-doping in the reduced graphene oxide (rGO). The optical absorption coefficients also showed a dependence on the rGO's reduction degree, with reduced samples displaying higher values, and sample thermally reduced at 300°C showing the highest absorption coefficient, due to the combined absorption of unaltered PbS QDs and the appearance of sp2 regions within rGO. The photogenerated current increased in most reduced samples, displaying the highest photocurrent the sample reduced at 400°C, presenting a 2500-fold increment compared to the NHM before reduction, attributed to an enhanced CC transfer from PbS QDs to rGO, as a consequence of an improved band alignment between them. These results show clear evidence on how the optoelectronic properties of NHMs based on semiconductor nanoparticles and rGO, can be tuned based on their configuration and the reduction process parameters.

中文翻译：

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基于 PbS 量子点和具有可调光电特性的还原氧化石墨烯的溶液处理纳米结构混合材料。

纳米结构杂化材料 (NHM) 有望改善多种材料在不同应用中的性能。在光电技术的情况下，调节这种 NHM 的光吸收的能力是一个吸引人的特性。连同将吸收的光转化为电荷载流子 (CC) 的能力，以及它们因此有效地传输到不同电极的能力。在这方面，基于类石墨烯结构和半导体 QD 的 NHM 是有吸引力的候选者，假设 NHM 保留了半导体 QD 的光吸收和 CC 光生特性，以及类石墨烯材料表现出的优异 CC 传输特性。在目前的工作中，使用 PbS 量子点 (QD) 和氧化石墨烯 (GO) 通过浸涂以逐层配置制造溶液处理的 NHM。之后，这些 NHMs 通过热或化学方法被还原。还原过程对 NHM 显示的最终光电特性有直接影响。所有还原样品的电阻率都有所下降，特别是化学还原的样品，下降了 107 倍；主要归因于还原氧化石墨烯（rGO）中的N掺杂。由于未改变的 PbS QD 的组合吸收和 sp2 区域的出现，光吸收系数还显示出对 rGO 还原程度的依赖性，还原的样品显示出更高的值，并且样品在 300°C 热还原时显示出最高的吸收系数在 rGO 内。大多数还原样品中的光生电流增加，显示出样品在 400°C 下还原的最高光电流，与还原前的 NHM 相比增加了 2500 倍，这归因于从 PbS QD 到 rGO 的 CC 转移增强，这是由于改进了它们之间的带对齐。这些结果清楚地表明了基于半导体纳米颗粒和 rGO 的 NHM 的光电特性如何可以根据它们的配置和还原工艺参数进行调整。