Carbon Nanotube/Polymer Composites as a Highly Stable Hole Collection Layer in Perovskite Solar Cells

TLDR

Organic‑inorganic perovskite solar cells have rapidly advanced, achieving efficiencies above 19 % within four years, yet their long‑term stability remains insufficiently explored. This study targets the thermal instability of perovskite cells and proposes replacing the organic hole‑transport layer with polymer‑functionalized single‑walled carbon nanotubes embedded in an insulating polymer matrix. The authors fabricate a hole‑collection layer by dispersing polymer‑functionalized SWNTs in an insulating polymer matrix, forming a composite that replaces the conventional organic transport material. The composite delivers up to 15.3 % power‑conversion efficiency with an average of 10 ± 2 %, shows markedly slower thermal degradation and enhanced water resistance, indicating a significant step toward durable high‑efficiency perovskite solar cells.

Abstract

Organic-inorganic perovskite solar cells have recently emerged at the forefront of photovoltaics research. Power conversion efficiencies have experienced an unprecedented increase to reported values exceeding 19% within just four years. With the focus mainly on efficiency, the aspect of stability has so far not been thoroughly addressed. In this paper, we identify thermal stability as a fundamental weak point of perovskite solar cells, and demonstrate an elegant approach to mitigating thermal degradation by replacing the organic hole transport material with polymer-functionalized single-walled carbon nanotubes (SWNTs) embedded in an insulating polymer matrix. With this composite structure, we achieve JV scanned power-conversion efficiencies of up to 15.3% with an average efficiency of 10 ± 2%. Moreover, we observe strong retardation in thermal degradation as compared to cells employing state-of-the-art organic hole-transporting materials. In addition, the resistance to water ingress is remarkably enhanced. These are critical developments for achieving long-term stability of high-efficiency perovskite solar cells.