Research On The Regulation And Scalable Fabrication Of Wide-Bandgap Perovskite

In recent years,organic-inorganic halide perovskite materials have attracted considerable attention due to their excellent properties such as high absorption coefficient,adjustable bandgap and solution processability.And the champion power conversion efficiency（PCE）of perovskite solar cells（PSCs）has reached 25.7%.To break the Shockley-Queisser limit of single-junction solar cells,tandem solar cells are assembled to fully utilize the solar spectrum and further improve efficiency.As a result,a series of tandem cells with PSCs as top sub-cells are born on demand,such as perovskite/silicon tandem cells,perovskite/perovskite tandem cells,perovskite/copper indium gallium dieseline tandem cells,etc.Wide-bandgap（E_g=1.70-1.80 e V）PSCs are usually utilized as the top sub-cells in tandem cells,well matching with a bandgap of low-bandgap cells such as silicon cells.However,suffering from large open-circuit voltage(V_OC)deficit and photoinduced phase segregation,the performance enhancement of wide-bandgap PSCs and perovskite-based tandem cells are hindered.Moreover,the preparation of large-area high-efficiency wide-bandgap perovskite solar module（PSM）is very important for the industrialization of perovskite.In the scalable preparation process,nucleation and growth of wide-bandgap perovskite are out of control,and thus large-area high-quality perovskite films are hard to be prepared,limiting the development of PSCs.In this work,component engineering and interface engineering are combined to manipulate the nucleation and growth and enhance film quality,thus promoting the performance of PSCs and stability.Meanwhile,large-area wide-bandgap PSMs and perovskite/silicon tandem cells are also explored,which provides new insights for the commercial development of PSCs.The main research contents and conclusions are as follows:（1）We study the nucleation and growth of the wide-bandgap perovskite films prepared by spin coating method with and without anti-solvent.The nucleation and growth of perovskite are manipulated by the introduction of NMP into the perovskite precursor,and Pb I₂·NMP and Pb Br₂·NMP adducts are formed,suppressing the growth of solvent-coordinated perovskite complexes and the non-perovskite phase（δ-phase）.Therefore,high-quality wide-bandgap perovskite films can be easily prepared without the use of an anti-solvent.This method improves the surface morphology of perovskite films and reduces defects,delivering a champion PCE of 18.40%.（2）A two-dimensional（2D）/three-dimensional（3D）perovskite heterojunction interface structure is formed by 2-thiophenemethylammonium bromide（2-Th MABr）surface treatment,which passivates the defects,suppresses non-radiative recombination and facilitates the hole extraction.The PCE of the champion device increases from the initial 18.40%to 19.46%,with an open-circuit voltage increasing from 1.163 V to 1.219 V.Moreover,the stability is significantly enhanced.The unencapsulated device remains over 93.0%of the initial PCE after aging in the air for2000 hours,and the encapsulated device still keeps 80%of the initial PCE after 200-hour light illumination.（3）With the assistance of N₂ flow to remove the solvent,large-area high-quality perovskite films are easily fabricated by blade coating.The characterizations demonstrate that the smooth and dense perovskite films show a relatively small difference in film roughness and the average roughness is only 13.76 nm.The PSMs deliver an efficiency of 16.07%on 46.5 cm² and 13.03%on 123.0 cm²,respectively.The semitransparent wide-bandgap PSCs are fabricated with an optimal ITO transparent electrode layer,which are used to assemble 4-T perovskite/silicon tandem cells with the silicon heterojunction cell.The tandem cells with active areas of 0.16cm² and 1.0 cm² achieve efficiencies of 23.85%and 19.51%,respectively.