Low-Cost Alternative High-Performance Hole-Transport Material for Perovskite Solar Cells and Its Comparative Study with Conventional SPIRO-OMeTAD

This study reports two new, simple and cost-effective hole transporting materials for perovskite solar cells. These novel structures namely N-4, N-4, N-4, N-4'''.tetrakis(4-methoxyphenyl)-[1,1': 4', 1 '': 4 '', 1'''-quaterphenyl]- 4,4'''-diamine (TPA-BP-TPA), and (E)- 4', 4'''-(ethene-1,2-diyl) bis(N, N-bis(4-methoxyphenyl)[1 '',1'''- biphenyl]-4-amine) (TPA-BPV-TPA) are based on linear p-conjugated linkers and triphenylamine endcappers. These materials possess good solubility and appropriate highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. Upon testing them as hole transporting materials in perovskite solar cells, in particular, the device with TPA-BPV-TPA exhibits a higher power conversion efficiency (PCE) of 16.42%, which is almost equivalent to the PCE using the conventional expensive 2,2', 7,7'-tetrakis(N,N'-di-pmethoxyphenylamino)- 9,9'-spirbiuorene (SPIRO-OMeTAD) compound under similar conditions. Additionally, the device stability measured using this newly developed low-cost compound retains almost 87% of the initial performance after 10 days compared to standard SPIRO-OMeTAD-based devices. From this outstanding outcome it is revealed that simple triphenylamine-based hole-transporting materials with various kinds of pi-conjugated linkers can pave the way for developing a new generation of simple hole-transporting materials for low-cost perovskite solar cells.