Solution-Processable A<sub>2</sub>XY<sub>4</sub> (A = PEA, BA; X = Pb, Sn, Cu, Mn; Y = Cl, Br, I) Crystals for High Light Yield and Ultrafast Scintillators
Md Abdul Kuddus Sheikh, Dominik Kowal, Muhammad Haris Mahyuddin, Djulia Onggo, Francesco Maddalena, Cuong Dang, Roberto Calá, E. Auffray, Marcin E. Witkowski, Michał Makowski, Winicjusz Drozdowski, Daniele Cortecchia, Christophe Dujardin, Muhammad Danang Birowosuto
Abstract
Two-dimensional (2-D) Ruddlesden-Popper (RP) hybrid organic-inorganic perovskite (HOIP) crystals, A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> XY <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> [A = Phenethylammonium (PEA), Butylammonium (BA); X = Pb, Sn, Cu, Mn; Y = Cl, Br, I] have been a subject of interest for solution-processable scintillators for the past two decades, due to the possibility to grow high-quality and large crystals with low-cost techniques. We start the review from PEA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> PbBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> and BA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> PbBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> crystals, which have light yields >10 photons/keV and scintillation decay times < 15 ns. Then, we extend our review to iodide compounds from the perspective that the smaller bandgaps and the heavier anions can allow higher light yields and shorter absorption lengths, respectively. In our previous experiments, we observed that the iodide crystals are bright while they have 1 ns optical decay times. Another approach is the investigations of the ion-doped PEA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> PbBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> and BA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> PbBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> , in which Li-doped PEA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> PbBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> has 23 photons/keV light yields. An additional feature is the thermal neutron detection and the discrimination with gamma-ray. Finally, we investigate lead-free perovskite variants (Sn, Cu, and Mn) as they are more friendly to environments, and the emission is shifted from blue to green or red for better sensitivity with current X-ray imaging detectors. Unfortunately, the light yields are much lower than the Pb counterparts, while the decay times are considerably slower due to different exciton mechanisms. This comprehensive investigation helps us to direct our review to the identification of the ultimate 2-D RP HOIP scintillators with high light yield, ultrafast response, and environmental friendliness.