Hydrophobic Hydrogen‐Bonded Polymer Network for Efficient and Stable Perovskite/Si Tandem Solar Cells

Abstract

The pursuit of highly efficient and stable wide‐bandgap (WBG) perovskite solar cells (PSCs), especially for monolithic perovskite/silicon tandem devices, is a key focus in achieving the commercialization of perovskite photovoltaics. In this study, we initially designed poly(ionic liquid)s (PILs) with varying alkyl chain lengths based on density functional theory calculations. Results pinpoint that PILs with longer alkyl chain lengths tend to exhibit more robust binding energy with the perovskite structure. Then we synthesized the PILs to craft a hydrophobic hydrogen‐bonded polymer network (HHPN) that passivates the WBG perovskite/electron transport layer interface, inhibits ion migration and serves as a barrier layer against water and oxygen ingression. Accordingly, the HHPN effectively curbs nonradiative recombination losses while facilitating efficient carrier transport, resulting in substantially enhanced open‐circuit voltage (VOC) and fill factor. As a result, the optimized single‐junction WBG PSC achieves an impressive efficiency of 23.18%, with VOC as high as 1.25 V, which is the highest reported for WBG (over 1.67 eV) PSCs. These devices also demonstrate outstanding thermostability and humidity resistance. Notably, this versatile strategy can be extended to textured perovskite/silicon tandem cells, reaching a remarkable efficiency of 28.24% while maintaining exceptional operational stability.

Defect Passivation Enabled by Amphiphilic Polymer Additives for Perovskite Solar Cells with Suppressed Charge Recombination

“…Contact angle (CA) measurements of water droplets on the surface of the perovskite film with and without p­(HEMA- co -DEAMA) modification are conducted. As displayed in Figure d, the water contact angles of the p­(HEMA- co -DEAMA) modified perovskite film compared to the bare perovskite film increased from 36.1° to 73.8°, implying a better moisture resistance of p­(HEMA- co -DEAMA)-passivated perovskites . The unpackaged devices were also monitored to evaluate the influence of p­(HEMA- co -DEAMA) on improving the long-term stability in the atmosphere with 30% relative humidity at 20 °C.…”

“…As displayed in Figure 5d, the water contact angles of the p(HEMA-co-DEAMA) modified perovskite film compared to the bare perovskite film increased from 36.1°to 73.8°, implying a better moisture resistance of p(HEMA-co-DEAMA)-passivated perovskites. 31 The unpackaged devices were also monitored to evaluate the influence of p(HEMA-co-DEAMA) on improving the longterm stability in the atmosphere with 30% relative humidity at 20 °C. After being placed for 1000 h, the normalized PCE of the control device retains only 60% of its initial PCE (Figure 5e).…”