| Currently,organic-inorganic hybrid perovskite solar cells are the most promising thin film cells in the field of photovoltaic,which rely on their excellent photoelectric properties,extremely economical production costs,ease of fabrication and rapidly increasing photoelectric conversion efficiencies,and it has attracted continuous and extensive research and attention from academia and industry.The perovskite solar cells produced in the laboratory have grown rapidly from 3.8 % in 2009 to the highest photoelectric conversion efficiency of 25.2 % in just 12 years.Even though SpiroOMe TAD,as a key part of solar cells,plays a crucial role in the photoelectric conversion efficiency,device repetition rate and stability,the doping mechanism and hole transport mechanism of Spiro-OMeTAD have been in a state of intense controversy.This thesis aiming at these two problems,a reasonable explanation is proposed from the perspective of spectral analysis.Firstly,the problem of using Li-TFSI to doping Spiro-OMeTAD is studied.In order to control the variables from the experimental,the dopant used in the experiment is only Li-TFSI instead of Li-TFSI and t-BP are used together.First,we perform comprehensive optical characterization of the solution such as steady-state absorption spectroscopy(Abs),photoluminescence spectroscopy(PL),and transient fluorescence decay(PL-decay),meantime the experimental variables are strictly controlled between the corresponding samples.Then those solution were spin-coated,and the spectroscopic and electrical characterization continued to verify the conjecture that the doping of Li-TFSI on SpiroOMe TAD was a catalytic.This is the reason why Li-TFSI doping is used when SpiroOMe TAD is used as the hole transport layer in the device preparation process.Based on this,we give the optimal mixing ratio of Li-TFSI.Secondly,researched the mechanism of the amorphous Spiro-OMeTAD layer through ultra-violet(UV)light-soaking to enhance the conductivity.Pristine amorphous spiro-OMe TAD thin film devoid of any additives is utilized as the background reference to quantify the bonus in its conductivity owing to prolonged UV light-soaking,whereby ultimately ? 300 % conductivity enhancement is achieved without damaging the molecular structure.Spectroscopic evidences monitored in parallel with the electric test suggest the amorphous spiro-OMe TAD layer was prolonged exposed to intensive photoexcitation will result the molecular scale ordering.Combined absolute photoluminescence quantum yield and nanosecond-resolved photoluminescence analysis jointly evidence the promoted fast non-radiative deactivation of excited with prolonged UV light-soaking.Based on this,a long-range multiexcimer model is proposed,elucidating deconvolution of the spectroscopic evidences under prolonged UV photoexcitation and the subsequent positive effect in channeling intermolecular charge hopping.This study provides new insights into the widely used UV light-soaking posttreatment to hole conducting layer consisting of spiro-OMe TAD in emerging solutionprocessed optoelectronics.This thesis insight study the photoelectrochemical and physical process of the hole transport material Spiro-OMeTAD in the perovskite solar cells,in order to further promote the perovskite solar development for provides useful ideas and practices. |
PDF Full Text Request