Main content area

Interfacial Study To Suppress Charge Carrier Recombination for High Efficiency Perovskite Solar Cells

Adhikari, Nirmal, Dubey, Ashish, Khatiwada, Devendra, Mitul, Abu Farzan, Wang, Qi, Venkatesan, Swaminathan, Iefanova, Anastasiia, Zai, Jiantao, Qian, Xuefeng, Kumar, Mukesh, Qiao, Qiquan
ACS Applied Materials & Interfaces 2015 v.7 no.48 pp. 26445-26454
X-ray diffraction, annealing, electron transfer, electrons, microscopy, photovoltaic cells, temperature, titanium dioxide
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.