[en] Highlights: • Cabazole-based hole-transporting material CZ-TA was developed via one-step synthesis. • Perovskite solar cells (PVSCs) with 50 nm CZ-TA film achieved a maximum PCE of 18.32%, comparable to that with 200 nm spiro-OMeTAD. • CZ-TA improved the hole extraction and transport to afford impressive fill factors over 81%. • The unit cost of CZ-TA hole-transporting layer was only 1/80 of that of spiro-OMeTAD, paving its way for commercialization of low-cost PVSC technology. A carbazole-based hole-transporting material named 4,4′,4′′,4′′′-(9-octylcarbazole-1,3,6,8-tetrayl) tetrakis(N,N-bis(4-methoxyphenyl)aniline) (CZ-TA) has been developed through a one-step facile synthesis approach. The solution-processed planar perovskite solar cells (PVSCs) with 50 nm thick CZ-TA hole selective layer (HSL) contributes a power conversion efficiency of 18.32%, comparable to the most commonly used 200 nm spiro-OMeTAD (18.28%) HSLs. The improved hole extraction, transport and reduced recombination are found to endow CZ-TA-based devices with impressive fill factors over 81.0%. Importantly, the unit cost of HSL in PVSCs using CZ-TA can be as low as only 1/80 of that of spiro-OMeTAD, indicating that CZ-TA could be a promising candidate as HSLs for commercialization of the low-cost PVSC technology.