Investigation On P-type Semiconductor Materials And Surface Modification In Perovskite Solar Cells

In recent years,organic-inorganic halide perovskite solar cells?PSCs?have attracted wide attention.Its power conversion efficiency?PCE?has increased rapidly from 3.8%to22.7%.In typical PSCs,perovskite light absorber is usually sandwiched between the electron transport layer?ETL?and the hole transport layer?HTL?.The photo-generated electrons and holes are transferred through the n-type and p-type semiconductive interfacial layers,and collected by the transparent conductive electrodes and metal electrodes,respectively.Therefore,the proper charge transport interfacial layers can eliminate the Schottky contact between the metal-semiconductors,promote efficient charge separation and transportation at the interface,reduce interfacial recombination and improve the device efficiency.Furthermore,it is also beneficial to eliminate interfacial charge accumulation and hysteresis effect,and thus to enhance long-term stability of the device.In this thesis,we introduce a bi-functional molecule modified p-Li0.05Mg0.15Ni0.8O hole transport layer and a highly conductive p-type perovskite oxide semiconductor LaNiO3 as hole transport layer to improve performance of the devices,the main contents of the research are:a new type p-type perovskite oxide semiconductor?1?Basedonthedevicestructureof FTO/Li0.05Mg0.15Ni0.8O/5-AVA/MAPbI3/PCBM/BCP/Ag,the influences of 5-AVA modified Li0.05Mg0.15Ni0.8O hole transport layer on the device performance have been studied.By introducing a 5-AVA monolayer with bifunctional groups to modify Li0.05Mg0.15Ni0.8O surface,a high-quality perovskite film,the efficient hole transfer at the Li0.05Mg0.15Ni0.8O/MAPbI3 interface could be realized,and therefore the device power conversion efficiency is increased from 18.00%to 19.44%,with short-circuit current density of 21.80 mA cm^-2,open-circuit voltage of 1.129 V and fill factor of 0.79.More importantly,the interface stability of the 5-AVA modified is significantly improved,and the stability of the corresponding device in resistant to high bias poling is greatly improved.After high bias poling,the transient current is small and the forward and reverse J-V curves show good consistence.Based on this,the 5-AVA modified device shows good long-term stability.After 300 hours of continuous light soaking,its power conversion efficiency keeps more than 90%of its initial value under the maximum power point tracking condition.?2?Few studies have touched the p-type semiconductive interfacical materials in PSCs.Herein,a new type p-type perovskite oxide semiconductor,LaNiO3,has been explored.Based on the device structure of FTO/LaNiO3/MAPbI3/PCBM/BCP/Ag,LaNiO3represents the following characteristics and advantages:good conductivity of 3.827×10²S cm^-1,beneficially reduceing the internal resistance loss of the device;high optical transmittance,beneficially reducing the light absorption loss of only 2%in the device;appropriate valence band of-5.14 eV,matching well with the perovskite to reduce potential loss at the interface.Power conversion efficiency of the LaNiO3 based PSC has reached 9.92%,with short-circuit current density of 15.59 mA cm^-2,open-circuit voltage of 1.03 V and fill factor of 0.62.