Upconversion graphene quantum dots incorporation in performance enhancement of p-i-n perovskite solar cells

Photon upconversion with the potential to reduce spectral mismatch losses is a promising approach in improving solar cell performance. Utilizing the synergistic effect of quantum dots (QDs) along with upconversion (UC) properties in perovskite solar cells (PSCs) is an efficient strategy to extend the absorption spectrum from visible into near-infrared (NIR) range, which leads to an explosive evolution in improving solar cell performance. Herein, upconversion graphene quantum dots (UC GQDs, with the -4.5 nm particle size) are used to design an improved PSC. UC GQDs are incorporated into p-i-n PSCs by adopting interlayers, next to the hole transport layer (HTL), perovskite, and rear (Au) electrode, as HTL/UC GQD/PSK, PSK/ UC GQD/ETL, ETL/UC GQD/Au structure respectively. The designed CuI/PSK/UC GQD/PCBM/Au p-i-n PSC, by expanding the absorption range from near-infrared (NIF) photons into a visible region, increasing the light-harvesting capability following GQDs, and the suppression of charge recombination processes following a passive effect have shown an effective role in improving p-i-n PSCs performance. These subtly PSCs resulted in a high-power conversion efficiency (PCE) of 19.79% (18.06 +/- 1.73) compared to (15.07%, 14.97 +/- 0.10) pristine PSCs. The attractive hydrophobic property of the UC GQD has led to an increase in the long-term stability of the resulting solar cell under harsh environmental conditions.