Improved air stability of perovskite solar cells via solution-processed metal oxide transport layers

Abstract

Lead halide perovskite solar cells have recently attracted tremendous attention because of their excellent photovoltaic efficiencies. However, the poor stability of both the perovskite material and the charge transport layers has so far prevented the fabrication of devices that can withstand sustained operation under normal conditions. Here, we report a solution-processed lead halide perovskite solar cell that has p-type NiO(x) and n-type ZnO nanoparticles as hole and electron transport layers, respectively, and shows improved stability against water and oxygen degradation when compared with devices with organic charge transport layers. Our cells have a p-i-n structure (glass/indium tin oxide/NiO(x)/perovskite/ZnO/Al), in which the ZnO layer isolates the perovskite and Al layers, thus preventing degradation. After 60 days storage in air at room temperature, our all-metal-oxide devices retain about 90% of their original efficiency, unlike control devices made with organic transport layers, which undergo a complete degradation after just 5 days. The initial power conversion efficiency of our devices is 14.6 ± 1.5%, with an uncertified maximum value of 16.1%.

Self‐Organized Fullerene Interfacial Layer for Efficient and Low‐Temperature Processed Planar Perovskite Solar Cells with High UV‐Light Stability

“…Figure 4 a shows the steady‐state PL spectra of perovskite layer on TiO 2 , PCBM, and PCBM:PCBDAN. Consistent with the previous reports, the PL intensity of perovskite on the TiO 2 layer has a lower PL quenching than that of perovskite on the PCBM 43. This means that electrons cannot be efficiently transferred into the TiO 2 layer due to the lower electron mobility of TiO 2 , or the interfacial traps at the perovskite/TiO 2 interfacial 44, 45.…”

Recent Progress on the Long‐Term Stability of Perovskite Solar Cells

“…For example, NiO x and TiO 2 layers have recently been used for the hole and electron selective contacts, respectively, which made the perovskite device distinct from its organic counterpart. Yang and co‐workers reported a solution‐processed lead halide perovskite solar cell with a maximum value of 16.1% based on p‐type NiO x and n‐type ZnO nanoparticles as HTL and ETL, respectively 103. The device showed improved stability against water and oxygen degradation when comparing with the devices with organic charge transport layers.…”

“…Inorganic materials were explored to be good candidates as HTL owing to their intrinsically properties, such as NiO x ,103, 143 CuO x ,144 CuSCN,145 CuI,146 CuPc,147 etc. Compared to organic hole conductors, inorganic p‐type materials usually possess high chemical stability, hole mobility, low cost, and ease of synthesis.…”

Formation and Diffusion of Metal Impurities in Perovskite Solar Cell Material CH3NH3PbI3: Implications on Solar Cell Degradation and Choice of Electrode

“…Such degradation mechanism should be a serious concern for the solar cells in which the metal electrode is directly in contact with the MAPbI 3 layer without a hole transport layer (HTL) in between. The HTL‐free MAPbI 3 solar cells40, 41, 42, 43 have gained significant interest because the commonly used hole transport material, [2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine) 9,9′‐spirobifluorene] (spiro‐MeOTAD), suffers from costly processing and long‐term stability issues 44…”