Hydrophobic Dilauroyl Peroxide Improves the Electrical Performance and Stability of PTAA in both n-i-p and p-i-n Perovskite Solar Cells

Abstract

Stability degradation plagues both regular n-i-p and inverted p-i-n perovskite solar cells (PSCs), with the organic hole transport layer (HTL) constituting a key restricting factor. Poly(triarylamine) (PTAA) possesses intrinsic polymer characteristics and excellent thermal stability, rendering it a competitive candidate for high-performance PSCs applicable to both device structures. However, challenging p-doping procedures and vulnerability to humidity restrict its utilization. Herein, we introduced a hydrophobic dilauroyl peroxide (DP) with oxidation ability and a long-chain alkanes structure into the PTAA. Upon cleavage of the peroxide bond (−O–O−) of DP, two decanoyl free radicals are generated. These radicals seize the lone pair of electrons on the N atom of the triarylamine in PTAA, oxidizing PTAA into a positively charged radical PTAA•+, thereby achieving p-type doping of PTAA. This doping process enhances the electrical properties and transport characteristics of PTAA. Besides, the introduction of long-chain alkyl groups enhances the hydrophobicity of the PTAA film, increasing the water contact angle from 60.18° to 80.39°. As a result, the champion PCE of n-i-p PSCs increased from 23.49% to 24.82%, while that of p-i-n PSCs increased from 25.26% to 26.04%. Moreover, the humidity stability and thermal stability of the PSCs are enhanced. As a result, after the PSC aged for approximately 4752 h at 25 °C and 45% relative humidity, it still maintained 97% of its initial PCE.