Fig. 13. (a) Performance stability of unencapsulated PSCs based on mDPA-DBTP under ambient air storage (at a humidity level of 40 ± 5% and a temperature of 25 ± 3 °C). Reprinted with permission from ref. 151. (b) J–V curves of PSCs based on the YN2 HTM. Reprinted with permission from ref. 156. (c) J–V curves of the dopant-free HTM KR321 and doped spiro-OMeTAD as the reference. Reprinted with permission from ref. 157. (d) Maximum power point tracking of perovskite solar cells prepared in a single experiment, using undoped FA-CN (□), TPA-CN ( (◌), and doped spiro-OMeTAD (∇) as hole-transporting materials. The measurements were performed under UV-filtered simulated sunlight in an argon atmosphere. The initial power conversion efficiency was measured after storing the device under argon and in the dark for 24 h. Reprinted with permission from ), and doped spiro-OMeTAD (∇) as hole-transporting materials. The measurements were performed under UV-filtered simulated sunlight in an argon atmosphere. The initial power conversion efficiency was measured after storing the device under argon and in the dark for 24 h. Reprinted with permission from ref. 158. (e) GIWAXS pattern of the KR321 film coated with tetrachloroethane on a silica wafer (schematic illustration of the molecular surface arrangement). Reprinted with permission from ref. 157.