Scalable Fabrication of Stable High Efficiency Perovskite Solar Cells and Modules Utilizing Room Temperature Sputtered SnO₂ Electron Transport Layer

Abstract

Stability and scalability have become the two main challenges for perovskite solar cells (PSCs) with the research focus in the field advancing toward commercialization. One of the prerequisites to solve these challenges is to develop a cost-effective, uniform, and high quality electron transport layer that is compatible with stable PSCs. Sputtering deposition is widely employed for large area deposition of high quality thin films in the industry. Here the composition, structure, and electronic properties of room temperature sputtered SnO 2 are systematically studied. Ar and O 2 are used as the sputtering and reactive gas, respectively, and it is found that a highly oxidizing environment is essential for the formation of high quality SnO 2 films. With the optimized structure, SnO 2 films with high quality have been prepared. It is demonstrated that PSCs based on the sputtered SnO 2 electron transport layer show an efficiency up to 20.2% (stabilized power output of 19.8%) and a T 80 operational lifetime of 625 h. Furthermore, the uniform and thin sputtered SnO 2 film with high conductivity is promising for large area solar modules, which show efficiencies over 12% with an aperture area of 22.8 cm 2 fabricated on 5 × 5 cm 2 substrates (geometry fill factor = 91%), and a T 80 operational lifetime of 515 h.

Optimal film thickness and Sn oxidation state of sputter-deposited SnO 2 electron transport layers for efficient perovskite solar cells

“…For the SnO 2 films produced by CBD and spin coating of colloidal sols or sol–gel solutions, the reported optimum thicknesses are in the range of 30–50 nm, 30–39,44–46 and the sputter-deposited SnO 2 films are reported to have an optimal thickness of 17–40 nm. 54–57 We believe that the relatively thinner optimal thickness in our study is attributed to the better step coverage and higher uniformity of the SnO 2 films produced by our two-step deposition method.…”

Stability of perovskite PV modules

“…Replacement of TiO 2 by the SnO 2 layer can solve the issue from several points of view. First of all, as was shown by Qiu et al [15], that SnO 2 shows ten times higher conductivity (1.7×10 −3 S cm −1 ) than TiO 2 (10 −4 S cm −1 ). Secondly, the laser ablation of SnO 2 on top of TCO is easier than ablation of TiO 2 .…”

Isolating the Oxygen Adsorption Defects on Sputtered Tin Oxide for Efficient Perovskite Solar Cells

“…Since SnO 2 is an n-type semiconductor, using only Ar as the working gas during the sputtering process can easily generate a large number of oxygen vacancies, which can even lead to Sn 2+ becoming the main component in the film, affecting the band structure and electrical properties of the sp-SnO 2 film. Therefore, it is usually necessary to introduce a certain amount of O 2 into the sputtering working gas to improve the film quality. , We find that as the O 2 content (determined by the partial pressure) increases from 50 to 100%, the electron mobility of the sp-SnO 2 film measured by space-charge-limited-current (SCLC) measurements increases from 4.92 × 10 –4 cm 2 V –1 s –1 to 6.77 × 10 –4 cm 2 V –1 s –1 , indicating a reduction in internal defects of the sp-SnO 2 film and an improvement in the crystal quality (Figure a). This higher electron mobility is conducive to separating and extracting electrons from the perovskite layer.…”