Perovskite　solar　cells　have　drawn　significant　attention　due　to　their　excellent　photovoltaic　characteristics.　Upconversion　luminescence　material　modification　is　a　good　strategy　to　extend　the　device　response　to　the　near-infrared　region,　which　can　further　increase　device　efficiency.　By　adding　NaGdF4:　Er3+/Yb3+　nanorods　into　chlorobenzene　as　an　additive　in　the　antisolvent　to　modify　the　perovskite　layer,　we　found　that　upconversion　luminescence　nanoparticles　can　effectively　improve　the　perovskite　solar　cell　performance.　However,　unexpectedly,　the　photocurrent　contributed　by　the　infrared　part　is　lower.　The　efficiency　increase　of　perovskite　solar　cells　is　contributed　by　defect　passivation.　Further　research　shows　that　nanoparticles　can　effectively　fill　the　holes　and　gaps　at　the　grain　boundaries,　eliminate　surface　defects　of　the　perovskite,　and　modify　the　perovskite　film,　which　reduces　carrier　recombination　and　effectively　improves　the　device＇s　performance.　Finally,　the　power　conversion　efficiency　of　the　champion　device　can　reach　21.1%.　This　research　demonstrates　the　function　of　upconversion　luminescence　nanoparticles　in　PSCs　and　provides　a　simple　way　to　improve　the　device＇s　efficiency.