通过真空双源热蒸发制作高效CsPbBr3无机钙钛矿太阳电池-高斐

通过真空双源热蒸发制作高效 CsPbBr3无机钙钛矿太阳电池 高斐，刘生忠，雷婕 陕西省先进能源器件重点实验室 ， 陕西师范大学 材料科学与工程学院 西安 2018.11.10 Introduction 1. Organic-inorganic hybrid perovskite solar cell has attracted tremendous interest because of its combined advantages of high conversion efficiency and low processing cost. Poor stability 2. One effective way to enhance the stability of PSC is to use inorganic materials to replace labile organic components. Recently, all-inorganic halide perovskites of the type CsMX3 M Pb or Sn; X I, Br, Cl or mixed halides have been developed. CsSnI3, CsPbI3, CsPbI2Br, CsPbIBr2, CsPbBr3, CsPb0.9Sn0.1IBr2, and Cs0.925K0.075PbI2Br. CsPbBr3 PSC has the best stability. 3. Preparing method for inorganic CsPbBr3 or CsPbBr3-based films is important for obtaining good film quality, high device performance. Previously, almost all the CsPbBr3 films/solar cells were fabricated by a solution process. It is more challenging to obtain consistently uniform, large-area, high-quality CsPbBr3 films. Vacuum thermal evaporation can easily deposit multiple layers of thin films over large areas, and the deposited films have good uniformity and flatness. There are relatively few studies on the fabrication of perovskite solar cells using vacuum thermal evaporation. Liu et al. first used dual-source vacuum thermal evaporation to fabricate a high-efficiency 15 CH3NH3PbI3-xClx PSC. Sequential and separating vacuum deposition methods were also developed to improve the preparation of CH3NH3PbI3 films. Thermal evaporation was also used to fabricate CsPbI3, CsPbI2Br, CsPbIBr2 inorganic PSCs. 4. We use dual-source vacuum thermal coevaporation to prepare CsPbBr3 films and fabricate planar CsPbBr3 solar cells. We studied the effects of substrate temperature, evaporation rate ratio of CsBr to PbBr2, and annealing temperature on the CsPbBr3 film quality and corresponding photovoltaic performance. By optimizing the deposition and annealing conditions, we have prepared high-quality CsPbBr3 films and fabricated stable planar CsPbBr3 solar cells with a high efficiency of 6.95. Experimental and Results Fig. 1. a Schematic illustration of vacuum dual-source thermal coevaporation of CsBr and PbBr2 to deposit CsPbBr3 films. XRD patterns of the CsPbBr3 films on c-TiO2/FTO glass substrate for variations of b substrate temperature, Fig. 1. c evaporation rate ratio of CsBr to PbBr2, and d post annealing temperature. Fig. 2. SEM/AFM images of the a, d, and g as-deposited; b, e, and h 400 C; and c, f, and i 500 C- annealed CsPbBr3 films. Fig. 3. a UV-Vis absorption spectra, b Tauc plots Ahν2 vs hν curves Fig. 3. c PL spectra, d Time-resolved PL decay of the deposited CsPbBr3 films with various annealing temperatures of 25-550 C. Fig. 3. e Dark I-V curves for FTO/TiO2/CsPbBr3/PCBM/Ag devices with and without CsPbBr3 films annealing. Fig. 4. a Schematic diagram, b cross-sectional SEM image, and c energy level diagrams of a typical planar CsPbBr3 perovskite solar cell. PCE as a function of d evaporation rate ratio of CsBr to PbBr2 and e annealing temperature of the CsPbBr3 films. Fig. 5. a J-V curves, b PCE histogram of the planar CsPbBr3 perovskite solar cells with and without CsPbBr3 film annealing. c EQE spectra and integrated current density of the best cell with area of 0.09 cm2. dJ-V curves measured under reverse and forward scans for the best cells with area of 0.09 cm2. Fig. 5. J-V curves measured under reverse and forward scans for the best cells with area of e 1.00 cm2. f Stability measured in ambient air with the relative humidity of 30 in the dark of the best CsPbBr3 perovskite solar cell. Conclusion 1. We have demonstrated that high-quality inorganic CsPbBr3 perovskite films and high-efficiency planar CsPbBr3 solar cells can be fabricated by dual-source vacuum thermal coevaporation of CsBr and PbBr2. 2. The optimal deposition conditions of CsPbBr3 films are a substrate temperature of 300 C, evaporation rate ratio of CsBr to PbBr2 of 0.71, and post-annealing temperature of 500 C for 15 s. The deposited films are extremely uniform and have large grains. 3. The best-performing device fabricated from the deposited CsPbBr3 film achieved a stabilized high conversion efficiency of 6.95 in small size 0.09 cm2 and 5.37 in large size 1 cm2. Furthermore, the fabricated CsPbBr3 cell has good long-term stability. 4. Dual-source thermal coevaporation is an effective approach for preparing high-quality CsPbBr3 films. We expect that this study will lay the foundation for developing large-area, high- stable-efficiency, CsPbBr3-based inorganic perovskite solar cells. 5. Further improve the efficiency of CsPbBr3 solar cell ① Doping; ② Interband cell. ③ Tandem cell. Thank you