Efficient and durable perovskite photovoltaics using dibenzothiophene arylamine derivatives for indoor energy harvesting†

Developing efficient and stable hole-transporting materials (HTMs) is critical for improving the performance of perovskite photovoltaic (PPV) devices, especially for indoor applications. Herein, we introduce two novel dibenzothiophene-based small organic molecule HTMs, labelled DBT-1 and DBT-2. These HTMs, featuring DBT as an acceptor and methoxy-substituted diphenylamine as a donor group, were designed to improve PPV devices' stability, charge transport properties, and efficiency. Theoretical studies confirmed the distinct geometries of the HTMs, revealing a more delocalized electron distribution in DBT-2 than in DBT-1, resulting in enhanced electronic properties. Optoelectronic properties revealed that both HTMs have higher highest occupied molecular orbital (HOMO) energy levels than perovskite, ensuring efficient hole extraction. When integrated into indoor perovskite photovoltaic (IPPV) devices, the DBT-2 HTM achieved a remarkable power conversion efficiency (PCE) of 33.32% under 1000 lux LED lighting, outperforming Spiro-OMeTAD-based devices by 28.13%. Notably, the hydrophobic nature and uniform film morphology of DBT-2 contributed to enhanced stability. Furthermore, after 200 hours of thermal stress at 80 °C, both HTMs demonstrated outstanding thermal stability, maintaining 91% of their initial efficiency. These results indicate that DBT-2 is a promising dopant-free HTM for efficient, reliable, and cost-effective PPVs, particularly in indoor applications. The high performance and durability of these materials make them strong contenders for next-generation indoor photovoltaic applications.