Designing an efficient graphene quantum dot-filled luminescent down shifting layer to improve the stability and efficiency of perovskite solar cells by simple optical modeling.

Degradation of perovskite material under UV light is a problem hampering the practical application of perovskite solar cells (PSCs) despite attaining high efficiency. This paper studies the application of a luminescent down shifting (LDS) layer containing graphene quantum dots (GQDs) on top of a PSC as an efficient strategy to improve the stability and light harvesting efficiency of PSCs under UV light. With absorption and emission bands in the UV and visible regions respectively, and simple synthesis of GQDs with a high luminescence quantum efficiency (QE), GQDs are a suitable candidate as a down shifting material in the LDS layer. Here, a simple optical model is used to investigate the effect of parameters such as the concentration of GQDs, LDS layer thickness, absorption/emission bands of GQDs and the luminescence quantum efficiency on the performance of the LDS layer. The calculated results show that application of a GQD-filled LDS layer, with 94% QE and negligible RO and PA, on a PSC causes a remarkable enhancement in the incident photon to current conversion efficiency (IPCE) and thereby the short circuit current density ( ) in the 300-400 nm spectral range of more than 400%. This strategy is also very effective in improving the stability of the PSC by suppressing the UV light from entering the device.