Tailoring the Functionality of Additives for Enhancing the Stability of Perovskite Solar Cells

Abstract

In a two‐step procedure for fabricating perovskite films, the PbI2 layer formed on the substrate is converted to perovskite by reacting PbI2 with organic iodide. Excess PbI2 left after forming perovskite composition, however, might have an ill effect on device stability and current–voltage hysteresis, although it positively affects efficiency improvement. Additive engineering is reported here on to control the residual PbI2 in a two‐step procedure. A series of organic multi‐ammonium chloride derivatives are introduced into the PbI2 precursor solution for the first‐step coating, which results in an increase in the perovskite grain size. In addition, carrier lifetime is elongated due to the reduced trap density and the energetics are adjusted to facilitate the extraction of photogenerated carriers. The aminoguanidinium‐containing precursor leads to an improved power conversion efficiency (PCE) as compared to the bare PbI2 precursor mainly due to the significantly enhanced open‐circuit voltage and fill factor. Consequently, a PCE of 23.46% is achieved from the hysteresis‐less photovoltaic parameters and 93% of the initial PCE is maintained after aging for 1000 h in ambient conditions.

Ionic liquid-regulated PbI2 layers and defect passivation for efficient perovskite solar cells

“…This reduction in PbI 2 residues is of paramount importance for enhancing the stability of the device. 32,33 Subsequently, in the ultraviolet-visible (UV-vis) and photoluminescence (PL) test results, the control and FAAc-modified perovskite films exhibit nearly identical absorption thresholds and photoluminescence positions, further revealing no discernible effect on the lattice structure, aligning with the XRD results. Importantly, the UV-vis absorption spectrum highlights an enhanced light absorption capacity of the FAAc-modified film, which enhanced light capture and reduced carrier non-radiative recombination (shown in Fig.…”

Efficiency enhancement to 24.62% in inverted perovskite solar cells through poly (ionic liquid) bulk modification

“…5b reveals that the P[STFSI][Ppyri]-doped film exhibits a higher hydrophobicity, as indicated by a contact angle of 72.9°, compared to the control film with a contact angle of 56.7°. These results suggest that the -CF 3 hydrophobicity in P[STFSI][PPyri] effectively shields the perovskite material from moisture, thus contributing to the enhanced stability observed in the doped device [45] .…”