Research On Copper Selenide, Copper Selenide Oxide And Perovskite Thin Films For Solar Power Generation

The development and utilization of solar energy is an important way to solve the human energy crisis,and the direct conversion of solar energy into electric energy is an effective means of solar energy utilization.Thermoelectric materials for solar thermoelectric conversion and photovoltaic materials for solar photoelectric conversion have become one of the research hotspots.Focusing on the center of solar power generation,this thesis studied the crystalline,doping,and defect passivation of copper selenide（Cu2Se）thermoelectric thin films and copper oxide selenium（CuOSe）and perovskite（MAPbI3）photovoltaic thin films.The main results are as follows:1.A two-step method for preparing Cu2Se thin films by thermal evaporation and hot pressing was proposed for the first time.The effects of hot pressing temperature,time,and pressure on the crystallinity of Cu2Se films were studied.Finally,high crystallinityα-Cu2Se films were obtained at 280℃ and 2 MPa for 5 min.The fabricated Cu/Cu2Se structure can directly convert heat into electric energy,and the thermoelectric potential is 12.6 mV at 400 K and 17.8 mV at 500 K.This method requires lower temperature,shorter time,and less pressure than traditional hot pressing of bulk Cu2Se materials.2.By introducing Se films above and below the CuOSe composite films,the defects of holes and cracks in the composite films are filled,and the quality of the composite films is improved.The composite films have absorption in the whole solar spectrum.The photoelectric conversion efficiency of FTO/TiO2/Se/CuOSe/Se/Au solar cells is 2.04%.In addition,the ultra long carrier diffusion length of the CuOSe composite films measured by photocurrent scanning method was further confirmed by transient photovoltaic method and changing illumination area method.3.The green antisolvent ethyl acetate（EA）and acetylacetone（AA）additive was used to regulate the crystallization and passivate defects of perovskite films.The MAPbI3 perovskite films with uniform,compact,large grain size,less grain boundary and low defect density were prepared in this way.At the same time,the surfacial hydrophobicity of perovskite films have been enhanced.Under the optimal concentration（1%）of AA in EA,the photoelectric conversion efficiency（PCE）of MAPbI3 perovskite solar cells（PSCs）is boosted from 19.2%to 21.1%,and the stability in air is also increased.This method provides a green antisolvent-additive-engineering（AAE）strategy for improving the crystallinity of perovskite films,passivating defects,and fabricating efficient and stable PSCs.