The Preparation Of Electron Transport Layers At Low Temperature For Perovskite Solar Cells

Compared with the mainstream solar cell products currently on the market,perovskite solar cells have the advantages of low cost and simple preparation process,and have gradually become research hotspots since the advent of the world.At present,the photoelectric conversion efficiency of perovskite solar cells has been greatly improved,from the initial 3.8% to 23.7%.As an important component of perovskite solar cells,the electron transport layer not only determines the electron transport but also the growth of the perovskite film deposited thereon,thus affecting the photovoltaic performance of the perovskite solar cell.In this paper,a new method was developed to prepare an electron transport layer,and obtained a perovskite solar cell with high photoelectric conversion efficiency.1.At present,the SnO₂ electron transport layer has gradually replaced the Ti O₂ electron transport layer as a research hotspot for researchers.Although efficient organometallic halide perovskite solar cells have been prepared using SnO₂ as a highly efficient electron transport layer,the preparation of SnO₂ by a simple solution method at sufficiently low temperatures?<180??is still very challenging.In this work,we dissolved the tin powder with dilute nitric acid to form metastable stannous nitrate.The introduction of combustion method and the addition of acetylacetone as fuel successfully reduced the SnO₂ treatment temperature?150??,resulting in a uniform and dense SnO₂ film and mark the SnO₂ prepared by combustion method as cb-SnO₂.The SnO₂ prepared by spin-coating an alcohol solution of SnCl₂ is labeled as sc-SnO₂.Transmission spectroscopy indicates that the cb-SnO₂ film has high transparency?from 350 nm to the near-infrared region?.The contact angle test showed that the prepared cb-SnO₂ film had a small contact angle with water,and the perovskite solution could spread well on the surface of the cb-SnO₂ film.Scanning electron microscopy?SEM?images of the perovskite light-absorbing layer show that the prepared cb-SnO₂ electron transport layer facilitates the growth of the perovskite film deposited thereon,and can form a perovskite film with uniform and dense.Photoluminescence?PL?tests have shown that the cb-SnO₂ electron transport layer has good electron extraction capability.The impedance test shows that the photoelectrons generated by the perovskite layer can be rapidly transferred to the cb-SnO₂ electron transport layer,which reduces the accumulation of charge at the interface between the perovskite layer and the cb-SnO₂ electron transport layer,thereby improving the performance of the device.We prepared perovskite solar cells under different conditions.The efficiency of devices based on plasma-treated cb-SnO₂ electron transport layer reached 19.60%,while the efficiency of devices based on plasma-treated sc-SnO₂ electron transport layer was up to 16.99%.This shows that we have prepared a better performance SnO₂ electron transport layer at a lower temperature.2.BaSnO₃?BSO?is an n-type semiconducting perovskite oxide.Due to its excellent optical and electrical properties,it has received increasing attention in the past decade.One of its potential advantages is the possibility to tune its electronic or optical properties by doping.In this paper,we introduced a combustion method using acetylacetone as fuel to prepare La-doped BaSnO₃?LBSO?films at 150 ?,100?,450 ?,and 70 ?.We studied the effect of the sintering temperature of the electron transport layer on the performance of the perovskite solar cell.The photocurrent density-photovoltage?J-V?curve of the cell shows that the sintering of the electron transport layer at 150? is the optimal condition.And the photoelectric conversion efficiency of the perovskite solar cell obtained under the optimal conditions reaches 18.76%.The current-voltage?I-V?characteristic curve of the device with the structure of?FTO/LBSO/Au?indicates that the LBSO electron transport layer prepared at a sintering temperature of 150? has a higher conductivity.And it can effectively inhibit the electron hole recombination at the interface of the perovskite/electron transport layer,thereby improving the photovoltaic performance of the device.