Formulation of conductive nanocomposites by incorporating silver-doped carbon quantum dots for efficient charge extraction

Poly(3,4-ethylenedioxy thiophene):poly(styrenesulfonate) (PEDOT:PSS) has been investigated as a hole transport material in organic-inorganic hybrid perovskite solar cells (PSCs) with a p-i-n architecture. However, the intrinsic acidic nature of PEDOT:PSS induces interfacial protonation and degrades the quality of the thin film, resulting in low charge conductivity, low perovskite crystallinity, and poor device stability. In this work, we demonstrate the effect of adding carbon quantum dots doped with silver (Ag-CQDs) to the PEDOT:PSS hole transport layer (HTL) to improve charge extraction, increase electrical conductivity, and hence, enhance the performance of hybrid PSCs. The proposed method enables facile one-step hydrothermal synthesis of the Ag-CQDs in the presence of a nitrogen-containing carbon precursor. The incorporation of PEDOT:PSS containing Ag-CQDs in PSCs noticeably increased the short circuit current density (J_sc) in the optimised devices, enhancing the device performance and ensuring long-term durability of PSCs, compared with the pristine. The performance improvement is the result of highly efficient hole extraction because of the enhancement of electrical properties of PEDOT:PSS by Ag-CQD. It is also attributed to the improved perovskite crystallinity, which depends on the increased surface energy of HTL. This work provides an efficient route to realise more stable PSCs capable of delivering outstanding charge dynamics.