To overcome small- and indirect-bandgap nature of crystalline bulk Si, a lot of efforts have been made to utilize Si quantum dots (SQDs) in optoelectronic devices. By controlling the size of Si quantum dots (SQDs), it is possible to vary the energy bandgap based on quantum confinement effect, which can maximize the power-conversion efficiency (PCE) of solar cells due to the energy harvesting in a broader spectral range. Here, we first employ graphene transparent conductive electrodes (TCEs) for SQDs-based solar cells, showing a maximum PCE of 16.2%, much larger than ever achieved in bulk-Si solar cells with graphene TCEs. In this work, the graphene TCEs are doped with two kinds of materials such as AuCl₃ and Ag nanowires for efficient collection of the carriers photo-induced in SQDs. The encapsulation of the doped-graphene TCE with another graphene layer prevents the doping elements from being desorbed or oxidized, thereby making the PCE higher, its doping dependence more evident, and the long-term performance more stable. The observed unique solar cell characteristics prove to be dominated by the trade-off effects between doping-induced variations of diode quality, transmittance/sheet resistance of graphene, energy barrier at the graphene TCE/SQDs interface, and reflectance.

为了克服晶体体Si的小和间接的带隙性质，已经进行了许多努力以在光电子器件中利用Si量子点（SQD）。通过控制Si量子点（SQD）的大小，可以基于量子限制效应改变能带隙，由于在更宽的光谱范围内进行能量收集，因此可以最大化太阳能电池的功率转换效率（PCE） 。在这里，我们首先为基于SQDs的太阳能电池采用石墨烯透明导电电极（TCE），其最大PCE为16.2％，比具有石墨烯TCE的体硅太阳能电池所获得的最大PCE大得多。在这项工作中，石墨烯TCE掺杂有两种材料，例如AuCl ₃和Ag纳米线，用于有效收集SQD中光诱导的载流子。用另一石墨烯层包封掺杂的石墨烯TCE可以防止掺杂元素解吸或氧化，从而使PCE更高，其掺杂依赖性更加明显，并且长期性能更加稳定。事实证明，观察到的独特太阳能电池特性受掺杂引起的二极管质量变化，石墨烯的透射率/薄层电阻，石墨烯TCE / SQDs界面的能垒和反射率之间的权衡影响所支配。