The recent emergence of low-dimensional copper-based halide perovskite Cs3Cu2I5, for use in optoelectronics and radiation detection, has evoked considerable interest. Presently, Cs3Cu2I5 single crystals grown using solution methods barely have clearly defined crystal planes and the crystal quality remains inferior. In this work, we have achieved high-quality Cs3Cu2I5 single crystals featuring prominent crystal habit planes through reducing the growth rate by controlling the concentration of I− ions via the addition of formic acid. The slow reaction between I3− and formic acid at a lower growth temperature can effectively control the concentration of I− ions in the solution, thereby reducing the growth rate and extending the metastable growth range simultaneously. This optimized process can yield high-quality single crystals, with a reduced full width at half maxima (FWHM) of 0.047° for the X-ray rocking curve on the (002) natural crystal habit plane, a substantially improved energy resolution of 7.1% for a photon energy of 511 keV, and an increased absolute light yield to 39 000 photons per MeV. Our study demonstrates that the reaction-controlled growth may be an effective way to improve the crystal quality of the copper-based halide perovskite.
Qian Yao,Jiaming Li,Xuesong Li,Xiaoxin Zheng,Zungang Wang,Xutang Tao
Copper(I) halide perovskite Cs 3 Cu 2 I 5 has recently attracted tremendous interest and has been considered an exceptionally promising scintillator due to its high quantum yield. However, its slow scintillation decay time, previously considered an intrinsic property, is a significant drawback preventing its practical application and commercialization. But in this work, it is found that the high-quality Cs 3 Cu 2 I 5 single-crystal grown by the designed aqueous solution method surprisingly exhibits a fast scintillation decay time of 39 ns (82%), quite different from previous reports. This subversive change may be due to the high crystal quality with denser 0D structure and low trap density (6.41 × 10 8 cm –3 ), changing the excited-state structural deformation and accelerating the recombination of electrons and holes while directly reducing the prolongation of decay time caused by inherent defects. Moreover, the single-crystal with a rocking curve FWHM value of only 50.4˝ has a high optical transmittance (85%), a very high absolute photoluminescence quantum yield (PLQY, 97.76%), superior environmental stability, and excellent light-yield and energy resolution under different γ-ray sources ( 241 Am, 60 Co, 22 Na, 137 Cs, 152 Eu). These extraordinary properties pave the way for the subsequent development of practical applications.
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