Composition Regulation Of Absorbable Materials In Mesoscopic Perovskite Solar Cells

Organic-inorganic lead halide perovskite solar cells?PSCs?have drawn significant attention due to the dramatically increase in the power conversion efficiency?PCE?over the last few years.A certified efficiency now exceeding 22.7%has been obtained since their first application in solar cells in 2009.For the conventional perovskite solar cells,the perovskite film was fabricated by spin-coating method often suffers from uncontrolled morphological variations,pinholes and cracks.which result in poor reproducibility of photovoltaic performance.Meanwhile,the spin-coating method for the conventional perovskite device limits its large-scale manufacture and application.However,the hole-conductor-free printable mesoscopic perovskite solar cell?MPSC?employ a cheap carbon counter to replace Au electrode,which decrease the cost of materials.In addition,the MPSC was fabricated by a simple one-step drop-coating approach,which simplify its preparation process contributed to its large-scale manufacture and industrial application.We report on a simple one-step solution processing strategy to fabricate new stable mixed cation/mixed halide?5-AVA?_xMA_1-xPbI_3-y?BF₄?_y perovskites solar cells.The results showed that the power conversion efficiency of the optimized mixed?5-AVA?_0.034MA_0.966PbI_2.95?BF₄?_0.05 perovskite solar cells was substantially increased to 15.5%with a remarkably high V_OC of 0.970 V.We have analyzed different mixed perovskites focusing on the characterization of the charge recombination by means of intensitymodulated photovoltage spectroscopy?IMPS?.In addition,our study discloses that the incorporation of MABF₄ into the?5-AVA?_0.034MA_0.966PbI₃ perovskite helps to reduce the charge recombination in the mixed perovskite device,thus improving the open circuit voltage of the device.Furthermore,the new mixed perovskite was demonstrated to produce high-quality perovskite crystals and enhance the conductivity of the mixed perovskite.We incorporated differdent small organic molecules?5-AVAI,5-AVACl and 5-AVABr?into the pristine perovskite precursor solution to create new mixed cation/mixed anion?5-AVA?_xMA_1-xPbI_3-x?Y?_x?Y=Cl,Br,I?perovskites for the MPSC.We investigated the effect of different mixed perovskites on the properties and performance of the solar cells.The result of the J-V characteristics shown that the V_OC of the 5-AVABr based mixed perovskite device has significantly improved compared with 5-AVAI based mixed perovskite device.Furthermore,we incorporated MABr and MABF₄ into the?5-AVA?_xMA_1-xPbI_3-x?Cl?_x perovskite precursor solution to create new mixed cation/mixed anion AFB.And we incorporated MACl and MABF₄into the?5-AVA?_xMA_1-xPbI_3-x?Cl?_x perovskite precursor solution to create new mixed cation/mixed anion AFC.The results show that the AFB and AFC mixed perovskites films have fewer defects and higher crystallization quality,and prolonger the life of the carrier in the both mixed perovskite crystal.It was foud that the devices fabricated by AFC and AFB have faster J-V response and smaller hyeresis.According to the IMPS test,the accelerated response speed of J-V and reduced hysteresis for the AFC device were attributed to the faster ion transmission transport based on the AFC mixed perovskite.By mixing the perovskite MAPbI₃ with LiCl,an effective one-step drop-coating approach was developed to improve the performance of the hole-conductor-free printable perovskite solar cells.The LiCl-mixed perovskite exhibited superior electronic properties,by improving the conductivity of the perovskite layer enabling faster electron transport.LiCl-mixing also improved the crystallinity and morphology of the perovskite layer.As a consequence,perovskite solar cells prepared using the LiCl-mixed perovskite as light harvester produced higher performances compared with the pristine perovskite,improving the power conversion efficiency from 10.0%to 14.5%.We investigated the effects of different halogenated ionic compounds?LiCl,LiBr and LiI?on the properties and performance of MPSC.The results of photocurrent density versus voltage curves show that LiCl,LiBr and LiI mixed perovskites can improve the performance of the devices.The results show that the V_OC,J_SC and FF of the LiCl and LiI mixed perovskites devices have significantly improved compared with the control perovskite device.For the LiBr based device,the V_OC and FF was significantly enhanced,and the J_SC was decreased at the same time.The XRD results confirm the existence of the MAPbBr₃within the MAPbI₃ phase after heating.We found that the incorporating of LiCl,LiBr and LiI into MAPbI₃ perovskite precursor solution can improve the crystallization process of perovskite.Compared with the pristine perovskite film,the conductivity of the films prepared on LiCl,LiBr and LiI mixed perovskites was significantly.However,the electrical properties of LiCl was the best.