Photon upconversion, particularly via triplet–triplet annihilation (TTA), could prove beneficial
in expanding the efficiencies and overall impacts of optoelectronic devices across a
multitude of technologies. The recent development of bulk metal halide perovskites as triplet
sensitizers is one potential step toward the industrialization of upconversion-enabled
devices. Here, we investigate the impact of varying additions of bromide into a lead iodide
perovskite thin film on the TTA upconversion process in the annihilator molecule rubrene …