Recent advances and emerging trends of rare-earth-ion doped spectral conversion nanomaterials in perovskite solar cells

Organic–inorganic lead halide based perovskite solar cells (PSCs) have attracted unprecedented research interest over last decade. The high performance, combined with merits of low fabrication costs and ease of synthesis make PSCs promising alternate to state of the art silicon (Si) based solar cells. However, some inherent shortcomings of PSCs are hindering their market dominance over conventional photovoltaic technologies such as transmission loss of sub-bandgap photons, poor stability and hysteresis effects. Recently, use of rare earth (RE) ions doped nanomaterials in PSCs, has been identified as an effective means to address the aforementioned issues by expanding the range of absorption spectra minimizing the non-absorption loss of solar photons, enhancing light scattering and improving operational stability. This article reviews the recent progress in doping rare-earth (RE) ions in the building blocks of PSCs such as semiconductor electrodes and photoactive perovskite layers, and its use as a separate spectral conversion layer in PSCs. The effect of size, shape, constitution and concentration of RE-nanoparticles on the overall performance and device stability will be analyzed in detail. Moreover, we provide an outlook on the opportunities this newly developed field offers and the critical challenges faced in rationally and effectively using RE-ion-doped nanomaterials in PSCs for better operational stability and enhanced performance.