posted on 2019-05-15, 00:00authored byQi Zhang, Yujin Ji, Zhihui Chen, Daniele Vella, Xinyun Wang, Qing-Hua Xu, Youyong Li, Goki Eda
Recently,
some organic–inorganic hybrid perovskites (OIHPs)
have been reported to exhibit strong subgap broadband luminescence.
While the origin of such luminescence has been proposed by several
groups, a strategy to prepare OIHP with the desired subgap emission
properties has remained elusive. Here, we report controlled synthesis
of a broadband-emitting single-crystal 2D OIHP with an average quantum
yield of >80 %. We demonstrate that the intensity of broadband
emission
can be tuned by controlling the excess iodine ion concentration during
the synthesis in hydroiodic acid. We show that the emitters exhibit
characteristics of localized defects such as limited mobility and
saturation at high excitation power. Using density functional theory
calculations, we show that bond-state iodine interstitials are responsible
for the observed long-lived luminescence.