The Studies On Photoinduced Charge Separation/Recombination Dynamics In Qrganic-Inorganic Hybird Solar Cells

Organic-Inorganic hybird solar cell?HSC?technology is the focal point of study on solar cell.Compared to organic solar cells and inorganic cells,HSCs combine the high efficiency of inorganic cell and the low cost of organic solar cells.However,the working principle of HSCs is still unknown,which contrains the development of HSCs.Therefore,depper understanding on the HSCs working mechanisms must be obtained in order to further improve the performance of HSCs and promote the commercialization of HSCs.With the development of pulsed laser technology,the technology of transient absorption spectrum has made great headway,and it has been widely used in chemical and physical areas.It can be mainly used to measure the property of transient materials?excited state,free radical,and so on?generated by laser excitation.Among the various problems in solar cell working mechanism studies,three are most important: The generation,the recombination and the transport properties of photocarriers.Critical processes involving these three mechanisms mentioned above usually happen within the timescales of femtoseconds to millisecond.The aim of this thesis is to capture and study these ultrafast processes in HSCs with transient detection experimental techniques.In the first part,we introduce the basic principles and parameters of solar cells,and the development of HSCs.In the second part,we introduce the growth equipment and characterization messurement of the HSCs,and the materials of the HSCs.We focus on the femtosecond transient photoinduced absorption spectroscopy.In the third part and the forth part,we systematically study the separetion and the recombination properties of photocarriers in HSCs with femtosecond transient absorption spectroscopy?fs-TAS?.The HSCs we prepare are based on heterojunction of PbI₂/C₆₀ and Se/C60.We fit the dynamics process of characteristic signals in the transient absorption by a e exponent.The fitting results show that photoinduced carriers produce 600 fs after light excitation,then go through two recombinations whose lifetime is 6.7 ps and 128.8 ps in the heterojunction of PbI₂/C₆₀.In the heterojunction of Se/C60,the photoinduced carriers produce 1.6 ps after light excitation,then go through two recombinations whose lifetime is 6.1 ps and 86.1ps.