Presentation Information
[17a-M_124-1]Anhydride-Assisted Bulk Passivation Reduces Open-Circuit Voltage Loss in Pb-Sn Mixed Perovskite Solar Cells
〇(DC)Md Ataur Rahman1,2, Md. Abdul Karim2, Md. Emrul Kayesh2, Siliang Cao1, Shamim Ahmmed2, Kiyoto Matsuishi1, Ashraful Islam2 (1.Univ. of Tsukuba, 2.NIMS)
Keywords:
Pb-Sn mixed perovskite,Open-circuit voltage loss,Bulk passivation
Low-bandgap lead (Pb)-tin (Sn) perovskite solar cells (PSCs) have attracted significant attention for their prospective use as bottom cells in tandem solar cells. However, the low fill factor (FF) and large open-circuit voltage (VOC) loss arising from insufficient crystallization and significant non-radiative recombination losses act as major barriers to reaching high performance. In Pb-Sn mixed PSCs, a notable finding is that VOC remains lower than its expected value, with VOC loss ranging from 0.38 to 0.41 V, which is about 56% greater than the theoretical limit of 0.25 V. Therefore, reducing VOC loss and enhancing VOC toward the Shockley-Queisser limit are major ways for improving the power conversion efficiency (PCE) of Pb-Sn mixed PSCs. To address these issues, an anhydrous molecule, Trimellitic Anhydride (TMAH), is introduced into the perovskite precursor solution as a passivator. The -C=O and -COO- functional groups in TMAH established stable chelate complexes with undercoordinated Pb2+ and Sn2+ through electron transfer and thereby effectively modulated the nucleation and crystallization process. Also, TMAH, together with its hydrolysis product produced in the presence of moisture, Trimellitic Acid (TMA), shielded the perovskite from severe environmental influences. Accordingly, experimental results showed that TMAH treatment improved the humidity resistance and durability of perovskite films by inhibiting moisture-mediated degradation which is beneficial for long-term stability. Ultimately, TMAH boosted the photovoltaic performance with a PCE of 23.28%, a high VOC of 0.90 V (VOC loss of ~ 0.36 V) and a high FF of 81.2%. Finally, TMAH-treated devices maintained 80% of their initial efficiency after 2098 h storage in N2, 635 h storage in air and 283 h under 1-sun light soaking.