Enhanced efficiency and stability of p-i-n perovskite solar cells using PMMA doped PTAA as hole transport layers

For p-i-n perovskite solar cells (PeSCs), hole transport layer (HTL) plays a key role in its performance since it will affect the crystallization of the perovskite deposited on it. In this work, the insulating polymer polymethyl methacrylate (PMMA) was introduced into polytriarylamine (PTAA) matrix as mixed HTL to fabricate PeSCs. The efficiency and stability of PeSCs were significantly improved by employing PMMA as dopant compared to the control device (without PMMA). After optimizing the concentration of PMMA, the champion device achieved a peak power conversion efficiency (PCE) of 14.56 %, 33 % higher than the control device (10.92 %). The performance improvement can attribute to the increased hole conductivity of mixed HTL after ultraviolet ozone (UVO) treatment, and the optimized crystallization properties of perovskite. Meanwhile, the mixed HTL has better ability to block moisture from penetrating into the perovskite layer than pure PTAA layer. Hence, PeSCs based mixed HTL could keep good stability, retaining 80 % of their initial performance after 700 h under ambient conditions in comparison to the control device, which degrade to 64 % within the same time.