3D surface microstructure of silicon modified by QDs to improve solar cell performance through down-conversion and anti-reflection mechanism

Abstract

Improving the photoelectric conversion efficiency (PCE) of solar cells is an important subject for a wide range of photovoltaic research. One of the main reasons for low PCE is the mismatch between solar spectrum and solar cells. The use of down-conversion and anti-reflection mechanisms is a reasonable method to increase PCE. Down-conversion can convert low-absorbance photons in silicon solar cells into high-absorbance photons while the special 3D surface structure formed by the down-conversion material produces an anti-reflection effect to increase the PCE of the solar cell. In this study, cadmium selenide (CdSe) quantum dots (QDs) coating hybrid structure of monocrystalline silicon solar cells was proposed to increase the utilization. Here, the CdSe QDs were synthesized with a high absorption strength in the 300–500 nm and a photoluminescence (PL) peak at 628 nm. Benefiting from the larger absorption cross-section and weaker electron-phonon coupling characteristics of CdSe QDs, the down-conversion was achieved successfully, and the reflectance test of the CdSe QDs covered silicon solar cells also shows an anti-reflection effect. Therefore, by using the dual mechanism of down-conversion and anti-reflection, the PCE of solar cells was improved by the proposed system. The results show that the PCE of the CdSe QDs coating hybrid structure based monocrystalline silicon solar cells is increased by 1.42% from 14.45% to 15.87%. Besides, by using finite element method, the reflection reduction mechanism for lower transition layer was also simulated to further explain the experiment results. Due to the low synthesis cost of QDs, this work can be well integrated into the photovoltaic industry, which provides a new technical route and guidance for improving the PCE of silicon cells.