The Study Of High Stability Perovskite Solar Cells Based On SnS₂/SnS

Perovskite solar cells（PSCs）,as the third generation of solar cells,has achieved the power conversion efficiency（PCE）of 25.5%after more than 10 years of development due to its superb photoelectric properties,such as high absorption coefficient,wide absorption range and long carrier diffusion length.However,the biggest challenge of PSCs is stability.Sulphur in sulfur compound can interact with lead in perovskite,which plays an important role in improving device stability.In the previous work,the research group used SnS₂ as the electron transport layer to prepare PSCs,but the open circuit voltage(V_oc)loss was large due to the energy level mismatch,which led to poor device performance and stability.On this basis,homologous SnS was used to adjust SnS₂ bandgap structure to match the energy levels with perovskite in order to improve the performance and stability.Then the stable all-sulfur PSCs was prepared.The research contents are as follows:（1）Adjust SnS₂/SnS band gap to reduce V_oc loss of devices:The energy level was adjusted by optimizing SnS₂/SnS component content.After adjusting SnS₂/SnS band position,the V_oc of the devices was increased from 0.94 V to 1.08 V,and the PCE increased by 27.95%from 14.13%to 18.08%.The unencapsulated SnS₂/SnS PSCs could still maintain 85%of the initial efficiency after 500 h storage in the dryer,which was more stable than traditional Ti O₂ PSCs.That was because S inSnS₂/SnS could interact with Pb in perovskite and anchor the Pb.（2）Enhance the stability of PSCs by introducing sulphur-containing compounds:The devices containing S in each functional layer was prepared to further improve the device performance and stability.The results showed that the electrical conductivity and charge transfer properties of SnS₂/SnS were better than those of Sn O₂.With the addition of sulfide in perovskite,the film quality was improved,the grain size became larger,and the density of defect states decreased.With the introduction of the Cu SCN hole extraction layer,the ability of hole extraction was obviously enhanced.The PCE of 15.38%of the all-sulfur carbon-based PSCs was achieved.Stability tests showed that the device with sulfur in each functional layer had better stability than the device without sulfur which was caused by the interaction of S and Pb.