Study On Inverted Perovskite Solar Cells Based On Perovskite-substrate Interfacial Regulation

Inverted perovskite solar cells have attracted much attention due to their advantages of low temperature fabrication,low hysteresis effect,and easy fabrication of stacked devices.At present,the highest device efficiency has reached more than 24%.However,the maximum efficiency of the device is still lower than that of the formal device due to the high open-circuit voltage loss.In addition,the device’s stability still lags far behind that of commercial silicon cells,seriously hindering the development of future commercialization.The main reason is that the performance of interface is poor,which leads to serious non-radiative recombination and large energy loss.Therefore,how to modify perovskite-substrate interface is an important way to obtain high-performance inverted perovskite solar cells.Based on this,this thesis designs three optimization strategies from the perovskite-substrate interface regulation,and finally obtain high-performance inverted perovskite solar cells:（1）By introducing diethylenetriamine（DETA）small molecule between the substrate interfaces of perovskite,a high-performance inverted perovskite solar cell was constructed through an in-situ regulation strategy.Through a series of thin film and photoelectric characterization,it is found that DETA interface layer can improve the film quality of perovskite,improve the charge extraction and transferation,and reduce leakage of current in the device.The V_oc of the photovoltaic device was increased from 1.09 V to 1.10 V,and the J_sc was increased from 20.85 m A/cm² to 21.74 m A/cm²,and the repeatability of the device was significantly improved.A photoelectric conversion efficiency（PCE）of 18.2%was finally achieved.（2）A novel pyridine organic small molecule material,2-chloro-3-（hydroxymethyl）pyridine（Pymelcl）,is introduced into the perovskite substrate interface to improve the crystal growth of perovskite on the hole transport layer.A smooth and dense high-quality perovskite film with larger grain size was formed.The J_sc of the photovoltaic device was increased from 22.1 m A/cm² to 23.3m A/cm²,and the FF was increased from 75.5%to 76.5%.A photoelectric conversion efficiency（PCE）of 18.7%was finally achieved.（3）This project designs and prepares a new resonant organic molecule（Cz COPXZ）to construct a new hole-transporting layer,which can effectively regulate the crystallization process of perovskite film.Due to the fast self-adaptive tautomerization between multiple electronic states in neutral and charged resonance forms of the N^—C=O and N⁺=C-O^-forms,Cz COPXZ with dynamic adaptive charge transport properties will improve the hole extraction and transport capabilities of PSCs.In addition,Cz COPXZ can form Pb-O coordination with the perovskite layer to reduce the uncoordinated Pb ions in the film.By promoting the orientation growth of perovskite and reducing grain boundary formation,charge recombination and interfacial energy loss,the device efficiency and stability were simultaneously improved.The efficiency of the Cz COPXZ-based perovskite solar cell device increases to 19.3%,much higher than that of the PTAA-based device（17.9%）.We then further post-treat by phenethylammonium iodide,achieving a PCE of over 20%.More importantly,the device has good long-term photostability,and its performance is only 20%lower than the initial efficiency under continuous sunlight illumination at 65℃ for 1750 hours.