POS6-1633
Unraveling the Molecular Origin of Charge Transport and Stability in Non-Halogenated Phenothiazine Self-Assembled Monolayers for High-Performance Organic Solar Cells
When and Where
Nov 30, -0001
00:00 - 00:00
Room 301 (Grand Ballroom)
Presenter(s)
Mutiara Sirait (Pukyong National University)
Co-Author(s)
Abstract
Organic solar cells (OSCs) have attracted considerable attention as next-generation photovoltaic technologies owing to their mechanical flexibility, low cost, and solution-processability. Nevertheless, inefficient hole extraction and interfacial instability remain important challenges for achieving simultaneously high efficiency and long-term operational stability. Self-assembled monolayers (SAMs) have emerged as promising interfacial materials for replacing conventional hole-transport layers such as PEDOT:PSS; however, their photovoltaic performance can be strongly influenced by molecular packing, interfacial energetics, and structural stability. Herein, we develop a non-halogenated phenothiazine-based SAM, [(4-(10H-phenothiazin-10-yl)butyl)phosphonic acid] (PZPA), as an efficient hole-selective interfacial layer for OSCs. Compared with the reference MeO-2PACz, the sulfur-containing phenothiazine core of PZPA exhibits a deeper highest occupied molecular orbital level, facilitating favorable energy-level alignment, enhanced hole extraction, and stronger intermolecular interactions at the indium tin oxide interface. These molecular characteristics promote the formation of a compact and ordered SAM, leading to improved interfacial charge transport and device stability. When incorporated into PM6:Y6B0 bulk-heterojunction OSCs, PZPA enables a power conversion efficiency of 18.2% while exhibiting excellent thermal and ultraviolet stability, with only a 1.09% efficiency loss after prolonged illumination. Further photoelectron spectroscopy and light-soaking investigations reveal that the molecular structure of the SAM critically governs interfacial energetics and degradation behavior. Notably, integration of PZPA into PM6:L8-BO devices results in high power conversion efficiency of 19.7%, demonstrating the effectiveness of phenothiazine-derived SAMs as robust interfacial materials for simultaneously improving photovoltaic performance and operational durability.
