Study On The Effect Of Optimized Functional Layers To The Performance Of Perovskite Solar Cells

The perovskite materials have been used widespread in perovskite light-emitting diode and solar cells owing to the characters of narrow band gap,high carrier mobility and solution processability.As the new generation of thin film solar cells,organic-inorganic hybrid perovskite solar cells(PSCs)have shown an unprecedented rise in power conversion efficiency(PCE)up to 23.3%.In recent years,the research community about PSCs including the internal mechanism of the crystallization process and the working process of functional layers,which have been the research core about PSCs.This thesis mainly focuses on obtaining high-efficiency and stabilized PSCs simultaneously via adjusting crystallization process of the perovskite films and transporting layers by using additives,which perfect the charge extraction and reduce the defects of films.The main contents are described as follows:1.we have demonstrated a new strategy to passivate perovskite crystallization by incorporating g-C₃N₄ into the perovskite layer.The addition of g-C₃N₄ results in improved crystalline quality of perovskite film with large grain size by retarding the crystallization rate,and reduced intrinsic defect density by passivating charge recombination centers around the grain boundaries.In addition,g-C₃N₄ doping increases the film conductivity of perovskite layer,which is beneficial for charge transport in perovskite light-absorption layer.Consequently,a champion device with a maximum power conversion efficiency of 19.49%is approached owing to a remarkable improvement in fill factor from 0.65 to 0.74.2.To explore the effect of 2D metallic compound on the PSCs,Ga₂Se₃ was added into perovskite precursor solution.The results show the addition of Ga₂Se₃into the perovskite precursor solution can improve the crystal quality of perovskite film with good surface morphology and large grain size,which is beneficial to the charge extraction and transport.As a result,Ga₂Se₃ based PSCs deliver a PCE as high as19.61%.3.We have demonstrated a Pt-doped TiO₂ ETL by incorporating H₂PtCl₆ into the TiO₂ precursor via the reactions of hydrolysis and hydrothermal.Herein,Pt-doped TiO₂film with outstanding electron-transporting property and complete coverage on the substrates is reported by the authors.The improved cell performance is attributed to the enhancements of electron mobility and extraction ability owing to the alignment of energy levels of TiO₂ by Pt-doping.Pt-doping results in a tailed band level of TiO₂,which could suppress the charge accumulation at the interface of TiO₂-Pt/perovskite.Consequently,TiO₂-PtETL based PSCs deliver a PCE as high as 20.05%with an open-circuit voltage of 1.15 V,a fill factor of 0.75,a short-circuit current density of 23.83m A/cm² and remarkably alleviated hysteresis behavior.4.We have demonstrated an effective method to enhance the device performance of PSCs by modifying the Spiro-OMe TAD layer with flower-like MoS₂ nanoparticles.Herein,we developed a modified Spiro-OMe TAD layer by MoS₂ with 2H semiconducting phase and flower-like microstructure.The addition of MoS₂ played an important role in improving the hole mobility and enhancing the film stability of Spiro-OMe TAD.The resulting PSCs based on MoS₂-modified Spiro-OMe TAD HTL delivered a champion PCE as high as 20.18%.More importantly,the incorporation of MoS₂ could suppress the Li⁺migration in HTL owing to the strong adsorption ability and large specific surface area of flower-like MoS₂ nanoparticles.