"The results are extremely encouraging and imply that the perovskite is not fundamentally unstableinambient conditions."

"Currently, perovskite solar cells (PSCs) based on the "triple layer" architecture with a thick carbon back electrode have demonstrated perhapsthe most stable performance characteristics of all PSCs."

              —— Prof. Henry J. Snaith, University of Oxford

Nature Nanotechnology 2015, 10, 391

Adv. Energy Mater. 2016, 6, 1600014.

"Based on the pioneering work by Mei et al.（Han Group), we developed HTM-free solar cells, being at present the cheapest, fully printable low-cost deposition process."

—— Prof. MK Nazeeruddin, EPFL

Nature Comm. 2017, 8, 15684.

"Several groups have fabricated solar cells with micrometer-thick carbon top electrodes, which have been shown to have impressive stability and have been summarized in previous review articles. A combination of micron-thick carbon electrodes on perovskites infiltrated through mesoporous ZrO₂ and mesoporous TiO₂ have enabled no change in performance for unencapsulated solar cells after 1 year of storage in 54% RH ambient air and 1000 h under 1 sun in ambient air. Impressively, continued performance improvements on this mesoscopic, metal-free architecture have led to power conversion efficiencies exceeding 15%, and WonderSolar in China has begun deploying it at the module level."

——Prof. Michael D.McGehee, Stanford University

Chem. Rev. 2019,119,3418-3451