Near-infrared and ultraviolet to visible photon conversion for full spectrum response perovskite solar cells

Achieving full spectral response by utilizing the near-infrared (NIR) and ultraviolet (UV) parts of sunlight has undoubtedly become an important focus on increasing the power conversion efficiency (PCE) of perovskite solar cells (PSCs). Introducing a photoluminescent conversion layer by converting NIR or UV light into visible which can be effectively utilized by perovskite photoactive layer has been considered as a very promising route. In this work, on the basis of a novel NiO/Ag/NiO transparent electrode, the NaYF4: Yb3+, Er3+/NaYF4: Yb3+, Tm3+/Ag composite layers were introduced on the backlight side of the PSCs device by the pulsed laser deposition (PLD). This design enables multi-functional effects, harvesting NIR light and converting to visible, plasmonic scattering, reflection and luminescent enhancement. In this device, we observed considerable enhancement of PCE depending strongly on the power density of sunlight. Simultaneously, acting as an efficient encapsulation layer, the device also greatly boosted the long-term stability of PSCs in ambient conditions. Furthermore, a typical UV to visible Eu(TTA)2(Phen)MAA down-conversion (DC) layer was introduced on the incident light side of PSCs, leading to improvement of PCE and light stability of PSCs. Overall, the upconversion (UC) and DC effects give rise to the highest PCE performance of 19.5% and noticeable current density (Jsc) value of 27.1 mA cm−2 among the reported transparent PSCs, suggesting the great potential for application in spectral broadening and stability enhancement of PSCs.