Bae Sumin, Duff Matthew, Hong Jun Young, Lee Jung-Kun
Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA, 15261, USA.
Nano Converg. 2023 Jul 4;10(1):31. doi: 10.1186/s40580-023-00379-1.
A tradeoff between light absorption and charge transport is a well-known issue in PbS colloidal quantum dot (CQD) solar cells because the carrier diffusion length in PbS CQD films is comparable to the thickness of CQD film. We reduce the tradeoff between light absorption and charge transport by combining a Fabry-Perot (FP) resonator and a distributed Bragg reflector (DBR). A FP resonance is formed between the DBR and a dielectric-metal-dielectric film as a top transparent electrode. A SiO-TiO multilayer is used to form a DBR. The FP resonance enhances light absorption near the resonant wavelength of the DBR without changing the CQD film thickness. The light absorption near the FP resonance wavelength is further boosted by coupling the FP resonance with the high reflectivity of the Ag-coated DBR. When the FP resonance and DBR are combined, the power conversion efficiency (PCE) of PbS CQD solar cells increases by 54%. Moreover, the DBR assisted FP resonance enables a very thin PbS layer to absorb near infrared light four times more. The overall PCE of the thin PbS CQD solar cell increases by 24% without sacrificing the average visible transmittance (AVT). Our results show how to overcome the inherence problem of the CQD and develop a semi-transparent solar cell where the wavelength-selective absorption and the transparency for visible light are important.
在硫化铅胶体量子点（CQD）太阳能电池中，光吸收与电荷传输之间的权衡是一个众所周知的问题，因为硫化铅CQD薄膜中的载流子扩散长度与CQD薄膜的厚度相当。我们通过结合法布里 - 珀罗（FP）谐振器和分布式布拉格反射器（DBR）来减少光吸收与电荷传输之间的权衡。在DBR和作为顶部透明电极的介电 - 金属 - 介电薄膜之间形成FP共振。使用SiO - TiO多层膜来形成DBR。FP共振在不改变CQD薄膜厚度的情况下增强了DBR共振波长附近的光吸收。通过将FP共振与涂银DBR的高反射率耦合，进一步提高了FP共振波长附近的光吸收。当FP共振和DBR结合时，硫化铅CQD太阳能电池的功率转换效率（PCE）提高了54%。此外，DBR辅助的FP共振使非常薄的硫化铅层对近红外光的吸收增加了四倍。薄硫化铅CQD太阳能电池的整体PCE提高了24%，而不牺牲平均可见光透过率（AVT）。我们的结果展示了如何克服CQD的固有问题，并开发出一种半透明太阳能电池，其中波长选择性吸收和可见光透明度很重要。
