Increasing Photocurrent in Lead Sulfide Quantum Dots Solar Cells via Overpassing Active Layer Thickness Limitation
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PbS quantum dots solar cells(QDSCs) are promising candidates for solution-processed photovoltaics due to high accessibility in photocurrent conversion of NIR wavelength and showed a PCE of over 13% with room for improvement. Most of all, to overpass the efficiency limitation, the active layer thickness has to increase. However, the large refractive index difference between the PbS layer and the ZnO layers enhances optical interference. This phenomenon disturbs effective charge transport and decreases the maximum active layer thickness, reducing the capacity of light absorption. In this report, to overcome the optical interference effect, we fabricated textured ZnO layer based PbS QDSCs and conducted a relationship between optical interference and efficiency depending on active layer thickness. As a result, the device with a textured ZnO layer dramatically reduced optical interference with the ZnO layer and showed a higher Jsc and PCE with even over 400 nm active layer.