Abstract：Solid upconversion materials were prepared by using polydimethylsiloxane (PDMS) as polymer matrix to soak PdTPP (sensitizer) and DPA (emitter), the resulting solid upconversion system (PdTPP/DPA/PDMS) can prevent triplet-states of both sensitizer and emitter from quenching by oxygen, which can maintain stability for more than 10 h in the air. More importantly, PDMS can effectively enhance upconversion efficiency (UC) as high as 26.3%, which was the highest value in the reported literatures.