Photovoltaic & Optoelectronic Device Group

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Dual-color emitting Mn 2+ ion doped (PEA) 2 PbBr 4 perovskite towards white light-emitting diodes

Materials Chemistry Frontiers Royal Society of Chemistry (RSC) 5:2 (2021) 937-943

Authors:

Xupeng Gao, Xinyu Shen, Dingke Xue, Xin Li, Po Lu, Min Lu, Chunyan Li, William W Yu, Xue Bai

Abstract:

Mn 2+ ion doped 2D (PEA) 2 PbBr 4 perovskite nanocrystals with a high PLQY of 54% were synthesized using a crystallization method at room temperature, and efficient energy transfer from excitons to the Mn 2+ dopant was proven.

Observation of Charge Generation via Photoinduced Stark Effect in Mixed-Cation Lead Bromide Perovskite Thin Films

The Journal of Physical Chemistry Letters American Chemical Society (ACS) 11:23 (2020) 10081-10087

Authors:

Nhu L Tran, Madeline H Elkins, David P McMeekin, Henry J Snaith, Gregory D Scholes

Smart quantum dot LEDs with simulated solar spectrum for intelligent lighting.

Nanotechnology 31:50 (2020) 505207

Authors:

Yue Zhao, Dingke Xue, Jiatong Wang, Min Lu, Xinyu Shen, Xupeng Gao, William W Yu, Xue Bai

Abstract:

LED light bulbs that simulate solar spectrum were fabricated using CdSe core-shell quantum dots in combination with GaN blue-light chips. They exhibited excellent optical properties such as white CIE coordinates of (0.33, 0.33), high color rendering index (CRI) of 98 and correlated color temperature (CCT) of 5352 K. Moreover, a circuit system was used to control the LEDs so that the lighting spectrum changes with the time in a day to simulate the actual solar spectrum. The results show that the sun-like spectrum smart bulbs not only have good optical properties and high electrical stability, but also can automatically adjust their spectrum according to the time, making the lighting natural. This work makes sun-like lighting conditions for some special environments to promote the application of smart bulbs in smart lighting.

Time-Resolved Changes in Dielectric Constant of Metal Halide Perovskites under Illumination

Journal of the American Chemical Society American Chemical Society (ACS) 142:47 (2020) 19799-19803

Authors:

Min Ji Hong, Liangdong Zhu, Cheng Chen, Longteng Tang, Yen-Hung Lin, Wen Li, Rose Johnson, Shirsopratim Chattopadhyay, Henry J Snaith, Chong Fang, John G Labram

Atomic-scale microstructure of metalhalide perovskite

Science American Association for the Advancement of Science 370:6516 (2020) eabb5940

Authors:

Judy Kim, Henry Snaith, Michael Johnston, Laura Herz, Mathias Rothmann, Anna Juliane Borchert

Abstract:

Hybrid organic-inorganic perovskites are exciting materials for solar-energy applications whose microscopic properties are still not well understood. Atomic-resolution (scanning) transmission electron microscopy, (S)TEM, has provided invaluable insights for many crystalline solar-cell materials, and is used here to successfully image CH(NH2)2PbI3 thin films with low electron-radiation dose. Such images reveal a highly ordered atomic arrangement of sharp grain boundaries and coherent perovskite/PbI2 interfaces, with a striking absence of long-range disorder in the crystal. We demonstrate that beaminduced degradation of the perovskite leads to an initial loss of CH(NH2)2 + ions, leaving behind a partially unoccupied perovskite lattice, which explains the unusual regenerative properties of these materials. We further observe aligned point defects and climbdissociated dislocations. Our findings thus provide an atomic-level understanding of technologically important lead-halide perovskites.