Dopant-Free Mexylaminotriazine Molecular Glass Hole Transport Layer for Perovskite Solar Cells

The development of dopant-free organic hole transport materials (HTMs) is critical to the commercialization of perovskite solar cells (PSCs). Indeed, dopants are the key determinants for reducing photovoltaic stability. Here, we designed and synthesized three mexylaminotriazine molecular glass derivatives containing triphenylamino moieties with an easy and low-cost process. All three compounds show good solubility and film-forming ability, and they show promising results as HTMs in PSCs. The PSCs fabricated with these mexyaminotriazine-substituted HTMs reach efficiencies up to [power conversion efficiency (PCE)] 12.50% (12.40% stabilized). Furthermore, we also measured the long-term stability of PSCs using these HTMs, and the devices showed no significant decrease of their initial PCE after storage in the dark under an atmospheric environment with a relative humidity range of 40 to 50% for over 1000 h. This work indicates that methylaminotriazine derivatives are potential hole transport layer candidates for PSCs and provides strategic guidance for the further design of dopant-free HTMs.