Fabrication Of Highly Efficient NiO_x-based Perovskite Solar Cell

Organic-inorganic hybrid perovskite materials have been extensively studied for their superior photoelectric properties and low cost.Meanwhile,perovskite solar cells（PSCs）have also been rapidly developed in recent years.Typically,PSCs can be constructed with either a regular n-i-p structure or inverted p-i-n structure.Compared with regular PSCs,inverted PSCs have attracted more attention due to their lower fabrication temperature,suppressed hysteresis and good compatibility with tandem cells.For inverted PSCs,the hole transport layer plays an important role due to its decisive influence on hole transport and perovskite crystallization.Among a variety of p-type materials,nickel oxide（NiO_X）has been widely used due to its excellent chemical stability,suitable energy band structure and low cost.However,due to the serious carrier accumulation and recombination at the interface between NiO_X and perovskite,it is difficult for NiO_X based PSCs to achieve a higher short-circuit current density and open-circuit voltage,which severely limits the improvement of the device efficiency.Therefore,this thesis aims to adjust the NiO_X/perovskite interface by dipolar molecule,boosting the short-circuit current density of NiO_X-based PSCs,achieving inverted PSCs with high-performance.The main works are as follows:First of all,through alternating excitation from different directions to get time-resolved photoluminescence,we reveal the role that interface plays in determining the photo-generated carrier dynamics within perovskite films.Then we evaluate the effect of interface on carrier dynamics,and illustrate the two key factors:the concentration of interface defect states and the carrier distribution.Based on this discovery,to realize the optimization of carriers’behavior,a dipolar molecule（2-Thienylmethylamine,TPMA）is applied to regulate the interface.Then,the defect passivation effect of TPMA and the influence of dipole layer on carriers’extraction and transport at NiOx/perovskite interface are analyzed.Secondly,an efficient inverted perovskite solar cell is fabricated with introduction of an interface dipole layer of TPMA,and the role of interface dipoles in deciding device parameters is analyzed.At the interface,the direction of the extra electric field generated by oriented TPMA is the same as that of the original build-in electric field,which accelerates hole extraction and improves the short-circuit current density(J_SC)of the device（23.7m A/cm²）.Meanwhile,TPMA also improves the open-circuit voltage(V_OC)by defect passivation,realizing a synchronous enhancement of the J_SC and V_OC.Finally,the photoelectric conversion efficiency of device reaches 20.4%.We explore the multiple effects of interface dipoles on device key parameters and their quantitative correlations,and clarify the positive benefits of appropriate dipoles for realizing synchronous improvement of device current and voltage.In this work,dipolar molecules are used to regulate the interface of NiOx-based inverted PSCs to achieve synchronous enhancement of current and voltage,which provides a new strategy for the construction inverted perovskite solar cells with high-performance.