“…Further, due to the inherently low conductivity of the pristine spiro-OMeTAD, hydrophilic additives such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 4-tertbutyl pyridine (TBP), and so on, are usually necessary in order to improve the HTL conductivity, which induces poor device stability in air. [9,11,12] As one class of small-molecule HTMs, organometallic compounds that contain a delocalized 18 π-electron conjugated system with a metal ion located at the central cavity, have also attracted considerable research attentions and efforts in recent years due to their excellent hole extraction and transport ability when employed as HTMs in PSCs. [8,9,[11][12][13][14] So far, metal phthalocyanines (MPcs) are one of the most widely studied organometallic HTMs in PSCs.…”