The Application Of Conductive Polymer TFB Modified CuSCN Hole Transport Layer In Organic Solar Cells

Organic solar cells（OSCs）have become one of the most prospective technologies to cope with the energy dilemma and the worsening of environment due to its superiority of Semitransparency,low-cost processing and so on.To date,over 18%of power conversion efficiency（PCE）for single junction organic solar cell has been reported,but the PCE of OSCs is still far from the requirements of commercial application.The interface modification layers between the electrode and the light absorber affect the process of charge carriers transfer and extraction,and thus the interface modification layers have great effects on improving the photovoltaic performance of OSCs.Copper（I）thiocyanate（CuSCN）,a soluble p-type inorganic semiconductor,has was introduced into OSCs as hole transport layer（HTL）due to its ultra-high transparency,high hole mobility and excellent stability,and impressive photovoltaic performance has achieved.Nevertheless,poor interfacial contact between CuSCN and the light absorber affects the hole transfer and extraction,leading to increased recombination loss in OSCs.To solve the above problems,selecting appropriate interface materials to modify CuSCN which is an effective strategy.In this thesis,two schemes were designed to modify CuSCN film by utilizing conductive polymer Poly[（9,9-dioctylfluorenyl-2,7-diyl）-alt-（4,4’-（N-（4-butylphenyl）））]（TFB）for improving the photovoltaic performance of OSCs.The specific works are as follows:（1）The bilayer structure HTL（CuSCN/TFB（X）,X represents the rotation speed of TFB）is constructed by spin-coating the TFB interface modification layer on the surface of CuSCN thin film.The excellent charge extraction capability of CuSCN/TFB bilayer HTL is proved by its application in non-fullerene and fullerene OSCs with PM6:Y6 and PTB7-Th:PC₇₁BM as light absorber,respectively.The introduction of TFB interface modification layer tunes the work function of HTL,polishes the interfacial contact between the HTL and light absorber,which favors the hole extraction process in OSCs.In addition,compared to the reference cell based the pristine CuSCN HTL,CuSCN/TFB HTL based cells has lower recombination loss and higher exciton dissociation probability,and the domain size of Y6 in light absorber increases,which significantly improve the photovoltaic performance.Ultimately,CuSCN/TFB（2000）based cell achieves a champion PCE of 15.10%,which is 14%higher than that of the reference cell（13.15%）.（2）The hybrid HTLs（CuSCN:TFB（X）,X represents the ratio of TFB to CuSCN）was prepared by doping the conductive polymer TFB in the CuSCN solution,which was applied to the conventional bulk heterojunction OSCs with PM6:Y6 as the light absorber.Compared to the reference cell based the pristine CuSCN HTL,the photovoltaic performance of CuSCN:TFB（X）HTL based cells show significantly enhancement owing to the increased exciton dissociation probability and charge extraction processes,weak recombination losses.In addition,the matched work function of CuSCN:TFB（1.0%）,the improved interface contact between HTL and the light absorber,and the appropriate domain size of Y6 in the light absorption layer which also promote the improvement of PCE.Ultimately,CuSCN:TFB（1.0%）based cell achieves a champion PCE of 15.28%,which is 16%higher than that of the reference cell（13.13%）.