High performance perovskite solar cells based on β-NaYF4:Yb3+ /Er3+ / Sc3+ @NaYF4 core-shell upconversion nanoparticles

The introduction of upconversion materials as spectral converter into photovoltaic devices to harvest and convert near infrared photons to visible photons that can thus be absorbed by perovskite layer is a promising strategy for enhancing the performance of perovskite solar cells. Hence, beta-NaYF4:Yb3+ /Er3+ /Sc3+@NaYF4 rareearth doped upconversion nanoparticles with core-shell structure are synthesized. The doped rare-earth ions Yb3+ and Er3+ convert near infrared light to red and green light, and the Sc3+ ions enhance the upconversion luminescence efficiency, which broaden the absorption range of solar irradiation and generate extra photo current in the solar cells. The surface defects of beta-NaYF4:Yb3+ /Er3+ /Sc3+ is passivated by the even NaYF4 shell, which results in the obvious enhancement in upconversion emission intensity. Consequently, the perovskite solar cell based on the rare-earth doped upconversion nanoparticle mesoporous layer achieves a high power conversion efficiency of 20.19%, while the device based on TiO2 mesoporous layer gets an efficiency of 17.44%.