Promoting The Performance Of Perovskite Solar Cells With Dopping Materials

Organic-inorganic hybrid perovskite solar cell（PSCs）has developed rapidly in just over ten years because of its high molar extinction coefficient,low exciton binding energy,adjustable energy level width and long carrier diffusion length.The authentication efficiency has reached 25.5%from the initial 3.8%,which has exceeded the photoelectric conversion efficiency of previous generations of solar cells.Moreover,perovskite solar cells have simple preparation process,cheap materials and great research value.However,there are still many difficult problems will to be overcome in its future scientific research.First of all,the sensitivity of perovskite solar cells to light and water is very serious,and the passivation of internal defects and the modification of interfaces need researchers to continue to explore.In this thesis,for the first time,low-cost N-bromosuccinimide（NBS）is used as an effective P-type dopant in 2,2’,7,7’-tetrakis[N,N-bis（4-methoxyphenyl）amino]-9,9’-spirobifluorene（Spiro-OMe TAD）,which is the most frequently used hole transport material in PSCs.Two carbonyl groups in NBS can oxidize Spiro-OMe TAD well,which alleviated the problem of low hole mobility and conductivity caused by its structure.Under the optimum doping concentration（1%）,the hole mobility,conductivity and various properties of the device have been significantly improved,especially the hole mobility has increased from1.39×10^-4cm²·V^-1s^-1 to 4.92×10^-4cm²·V^-1s^-1,which is more than 3.5 times higher.The photoelectric conversion efficiency（PCE）of semiconductor devices has increased from 16.12%to 19.24%,and it can still maintain the efficiency of 83%after being stored indoors for 700hours,with good repeatability.It is of great significance to study how to improve the quality of electron absorption layer by adding appropriate dopants in anti-solvent for the preparation of efficient and stable perovskite solar cells.In this paper,organic small molecule hydroxylamine hydrochloride（Ha Hc）with two functional groups was added into anti-solvent（chlorobenzene）to try to improve the quality of perovskite thin films.Experiments show that hydroxyl groups in Ha Hc will form hydrogen bonds with Pb²⁺in perovskite,which will inhibit the decomposition of perovskite thin films and increase the stability of devices.Chloride ions will change the crystallization dynamics of perovskite thin films and slow down the film formation speed,thus obtaining perovskite thin films with lower defect density,larger grain size and less hysteresis effect.After adding Ha Hc,the open circle voltage and fill factor of perovskite solar cells increased obviously and the incident photon to current conversion efficiency increased from 17.19%to 18.96%.