A Homopolymer of Xanthenoxanthene‐Based Polycyclic Heteroaromatic for Efficient and Stable Perovskite Solar Cells

Abstract

Highly efficient perovskite solar cells typically rely on spiro‐OMeTAD as a hole transporter, achieving a 25.7 % efficiency record. However, these cells are susceptible to harsh 85 °C conditions. Here, we present a peri‐xanthenoxanthene‐based semiconducting homopolymer (p‐TNI2) with matched energy levels and a high molecular weight, synthesized nearly quantitatively through facile oxidative polymerization. Compared to established materials, p‐TNI2 excels in hole mobility, morphology, modulus, and waterproofing. Implementing p‐TNI2 as the hole transport layer results in n‐i‐p perovskite solar cells with an initial average efficiency of 24.6 %, rivaling 24.4 % for the spiro‐OMeTAD control cells under identical conditions. Furthermore, the p‐TNI2‐based cells exhibit enhanced thermostability at 85 °C and operational robustness.

Hole-transporting alternating copolymers for perovskite solar cells: thia[5]helicene comonomer outperforms planar perylothiophene analog

“…S4, ESI†). These values significantly exceed those of spiro-OMeTAD and PTAA, measured at 121 °C and 99 °C, 28 respectively. It is recognized that during the glass transition, a polymer's expansion coefficient undergoes a sudden change.…”

“…7–9 Nevertheless, its deep HOMO energy level poses challenges in achieving sufficiently high conductivity through air doping, resulting in suboptimal PCE when applied to n–i–p-type PSCs. Additionally, while a diverse array of molecular semiconductors and polymeric semiconductors with varied structures has found utility in PSCs, 10–28 only a select few materials successfully balance efficiency, stability, and cost.…”

“…S3, ESI†), significantly exceeding those of spiro-OMeTAD (153 °C) and PTAA (118 °C). 28 To further explore the merit of utilizing helicenes in constructing semiconducting polymers, we also synthesized a semiconducting polymer denoted as p-PET-E-POZ-E (Fig. 1(B)), composed of alternating PET, EDOT, POZ, and EDOT in the main chain.…”