title: Interfacial Study To Suppress Charge Carrier Recombination for High Efficiency Perovskite Solar Cells.
abstract: We report effects of an interface between TiO2-perovskite and grain-grain boundaries of perovskite films prepared by single step and sequential deposited technique using different annealing times at optimum temperature. Nanoscale kelvin probe force microscopy (KPFM) measurement shows that charge transport in a perovskite solar cell critically depends upon the annealing conditions. The KPFM results of single step and sequential deposited films show that the increase in potential barrier suppresses the back-recombination between electrons in TiO2 and holes in perovskite. Spatial mapping of the surface potential within perovskite film exhibits higher positive potential at grain boundaries compared to the surface of the grains. The average grain boundary potential of 300-400 mV is obtained upon annealing for sequentially deposited films. X-ray diffraction (XRD) spectra indicate the formation of a PbI2 phase upon annealing which suppresses the recombination. Transient analysis exhibits that the optimum device has higher carrier lifetime and short carrier transport time among all devices. An optimum grain boundary potential and proper band alignment between the TiO2 electron transport layer (ETL) and the perovskite absorber layer help to increase the overall device performance.
authors.affiliation: Center for Advanced Photovoltaics, Department of Electrical Engineering and Computer Science, South Dakota State University , Brookings, South Dakota 57007, United States.
authors.forename: Nirmal
authors.initials: N
authors.lastname: Adhikari
authors.affiliation: Center for Advanced Photovoltaics, Department of Electrical Engineering and Computer Science, South Dakota State University , Brookings, South Dakota 57007, United States.
authors.forename: Ashish
authors.initials: A
authors.lastname: Dubey
authors.affiliation: Center for Advanced Photovoltaics, Department of Electrical Engineering and Computer Science, South Dakota State University , Brookings, South Dakota 57007, United States.
authors.forename: Devendra
authors.initials: D
authors.lastname: Khatiwada
authors.affiliation: Center for Advanced Photovoltaics, Department of Electrical Engineering and Computer Science, South Dakota State University , Brookings, South Dakota 57007, United States.
authors.forename: Abu Farzan
authors.initials: AF
authors.lastname: Mitul
authors.affiliation: Center for Advanced Photovoltaics, Department of Electrical Engineering and Computer Science, South Dakota State University , Brookings, South Dakota 57007, United States.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Center for Advanced Photovoltaics, Department of Electrical Engineering and Computer Science, South Dakota State University , Brookings, South Dakota 57007, United States.
authors.forename: Swaminathan
authors.initials: S
authors.lastname: Venkatesan
authors.affiliation: Center for Advanced Photovoltaics, Department of Electrical Engineering and Computer Science, South Dakota State University , Brookings, South Dakota 57007, United States.
authors.forename: Anastasiia
authors.initials: A
authors.lastname: Iefanova
authors.affiliation: Shanghai Electrochemical Energy Devices Research Center, School of Chemistry and Chemical Engineering and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University , Shanghai 200240, People's Republic of China.
authors.forename: Jiantao
authors.initials: J
authors.lastname: Zai
authors.affiliation: Shanghai Electrochemical Energy Devices Research Center, School of Chemistry and Chemical Engineering and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University , Shanghai 200240, People's Republic of China.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Qian
authors.affiliation: Functional and Renewable Energy Materials Laboratory, Department of Physics, Indian Institute of Technology , Ropar, Punjab 140 001, India.
authors.forename: Mukesh
authors.initials: M
authors.lastname: Kumar
authors.affiliation: Center for Advanced Photovoltaics, Department of Electrical Engineering and Computer Science, South Dakota State University , Brookings, South Dakota 57007, United States.
authors.forename: Qiquan
authors.initials: Q
authors.lastname: Qiao
keywords: Kelvin probe force microscopy; back recombination; charge transport; interface engineering; perovskite film