Fabrication And Performance Study Of Anode Buffer Layers For All Spray Coated Solar Cells

Spray coating method for the fabrication of organic solar cells?OSCs?,due to the low-cost and large-area production,has drawn lots of interest in the past decades and become to the highlight of scientific research.Meanwhile,it is also well known that anode buffer layers?ABLs?play significant roles in improving charge transport and increasing efficiency for the inverted OSCs.Transition metal oxides?TMOs?have been considered as a kind of excellent material of ABLs for device application due to their outstanding hole-transporting capability and stability.However,most of TMOs buffer layers are fabricated by using vacuum thermal evaporated technique or sol-gel method with high temperature annealing,leading to the increased energy consumption and low production speed.It limits on these TMOs for further large scale industrial application.Therefore,it is important to realize a path towards the commercialization of spray coated OSCs.Firstly,a facile all spray fabrication routine was used to fabricate OSCs,in which a molybdenum oxide?MoO₃?micro array was directly deposited on the active layer by introducing a multicomponent solvent system?MSS?,and the influence of hole transporting property on the OSC performance was studied.Therefore,the main innovations of this work are:?1?A facile all spray fabrication routine was used to fabricate OSC.In particular,all layers of the OSC except the silver anode were fabricated by ultrasonic spray-coating method under atmospheric condition,which was suitable for large-scale fabrication of OSCs and compatible with roll-to-roll process.?2?A MSS was introduced to optimize the morphology of ultrasonic spray-coated MoO₃micro-arrays.The Mo O₃ micro arrays become smooth via using optimized MSS,and improve the interfacial contact between donor and anode.Ultimately,an all spray-coated device base on P3HT:PC₆₁BM system with PCE of 3.4%was obtained.Secondly,a TMO of tungsten trioxide?WO₃?as the ABL is prepared by decomposing ammonium tungstate(?NH₄?10W₁₂O₄₁)?AT?in air atmosphere by a low-temperature ultrasonic spray pyrolysis?USP?method instead of vacuum vapor deposition techniques.By using the obtained ABL of WO₃,a mostly spray-coated OSC except electrode was fabricated.The USP processed WO₃ ABL shows the low roughness,matched energy level,and high conductivity,resulting in high charge transport efficiency and suppressive recombination.Compared to the OSC based on vacuum evaporated WO₃ ABL,the performance of USP processed WO₃ based device shows an improvement of power conversion efficiency.To realize the uniform films for large area OSCs,the mechanism of USP process is also discussed.Finally,a large area OSC was successfully realized.The main innovations of this work are:?1?It is the first time to use a low-decomposition-temperature AT solution as a precursor to the prepare the WO₃ thin films,and the properties of WO₃ film as well as the mechanism of ultrasonic spray pyrolysis process are investigated.?2?The spray-coated WO₃ film was used as the ABL,all layers except the silver anode for OSC were processed by ultrasonic spray coating method under ambient condition.?3?A large area OSC?25 cm²?with a PCE of?1%has been achieved with the assistance of the USP processed WO₃film.In summary,this work significantly enhances the illumination of the preparation and application of low temperature-processed ABLs,and illustrates the potential of large area,all spray coated OSCs for the sustainable commercial fabrication.