Controlled growth of perovskite KMnF3 upconverting nanocrystals for near-infrared light-sensitive perovskite solar cells and photodetectors

Utilization of the photon upconversion (UC) in Pb halide-based perovskite solar cells (PVSCs) and photodetectors is a potential strategy towards broadening the spectral response from the visible to the near-infrared region and decreasing the non-absorption loss of solar energy. Nevertheless, the implementation of upconverting nanomaterials in these photoelectric devices still faces some barriers. Herein, we report a facile and ethylenediamine tetraacetic acid disodium (EDTAD)-assisted hydrothermal approach for growth of rare-earth-element-doped KMnF3 nanocrystals with controllable size and a singular red upconverting emission. EDTAD was demonstrated as a useful chelating agent to regulate the nanomaterial size, morphology and UC emission properties. KMnF3:Yb3+, Er3+ nanocrystals assisted by EDTAD achieved an intense single-band red UC emission. The formed singular UCNCs were successfully applied as an additive to enhance the photovoltaic performance of the PVSC devices. We found proper molar ratio UCNCs as an additive to the perovskite precursor facilitated the growth of semiconductor perovskite, inducing the development of the perovskite film with improved crystallinity, compact grains and fewer defects. At an optimum molar proportion of UCNCs, the mean power conversion efficiency (PCE) of 18.73% was acquired for PVSCs with KMnF3:Yb3+, Er3+ under AM 1.5G, demonstrating a prominent improvement over 25% in average PCE relating to the corresponding value (14.94%) of the PVSC device without UCNCs. Moreover, this singular red emission UCNCs-embedded PVSC was able to work as a photodetector under 980 nm illumination and with a responsivity of 0.26 mA/W.