Perovskite materials have been immensely investigated for solar cell applications in the past few years. The latest efficiency record is in excess of 20%. On the other hand, most perovskite solar cells suffer from degradation when being operated in air. The short lifetime has become an urgent challenge that need be addressed and solved. Among the various layers of a perovskite cell with the standard architecture (i.e. the starting substrate is FTO with a TiO2 blocking layer), the outmost layer (except the top electrode) is the hole transport layer (HTL), which is expected to play an important role in air stability. My group has recently studied a commonly used HTL in the perovskite solar cells, which consists of 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-MeOTAD) doped with Li-bis(trifluoromethanesulfonyl)-imide (LiTFSI). A combined microscopy study by AFM, cross sectional Scanning Electron Microscopy, optical microscopy and Fourier Transform Infrared microscopy reveals the presence of a surprisingly high density of pinholes that form channels across the doped spiro-MeOTAD film. These pinholes may play a major role in the degradation processes of perovskite solar cells. This is further confirmed by the rapid decreasing efficiency of perovskite solar cells with solution prepared doped spiro-MeOTAD layers when exposed to air. Strategies to solve these issues will also be discussed.