Letian Dou Group

The group welcomes a new graduate student Dharini Varadharajan. Dharini got her BS in Chemical Engineering from Anna University in 2020. She will be co-advised by Prof. Boudouris and Prof. Dou and she will work on organic radical-perovskite hybrid materials and optoelectronic devices. Welcome to the group!

The group is selected for an award by Department of Energy, Solar Energy Technologies Office (SETO), aiming at developing stable perovskite materials, solar cells and mini-modules. This is a joint effort with Prof. Brett Savoie (simulation) and Prof. Jianguo Mei (manufacturing). DOE news release can be found here. Big congratulations!

Kang and Linrui’s work on Lead-free organic-perovskite hybrid quantum well LEDs has been published in ACS Nano. Congratulations! Read the story here.

We report Sn(II)-based organic–perovskite HQWs employing molecularly tailored organic semiconducting barrier layers for efficient and stable LEDs. Collaborating with Libai Huang group, we demonstrate the energy transfer from organic barrier to inorganic perovskite emitter occurs faster than the intramolecular charge transfer in the organic layer. Incorporating a bulky small bandgap organic barrier in the HQW, charge transport is enhanced and ion migration is greatly suppressed. We demonstrate a HQW-LED device with pure red emission, a maximum luminance of 3466 cd m^–2, a peak external quantum efficiency up to 3.33%, and an operational stability of over 150 h, which are significantly better than previously reported lead-free perovskite LEDs.

We welcome Catherin Galvis Guiral from Universidad Nacional de Colombia, department of chemical engineering to join us for 6 months. Catherin will be co-advised by Prof. Dou and Prof. Boudouris working on radical-organic hybrid electronics. Welcome to the group!

Aihui and Kang’s work on highly efficient halide perovskite light-emitting diodes via molecular passivation has been published in Angewandte Chemie International Edition. Big congratulations!! Read the story here.

Metal halide perovskites are promising for applications in light‐emitting diodes (LEDs), but still suffer from defects‐mediated nonradiative losses, which represent a major efficiency‐limiting factor in perovskite‐based LEDs (PeLEDs). Reported here is a strategy to synthesize molecular passivators with different anchoring groups for defects passivation. The passivated perovskite thin films exhibit improved optoelectronic properties as well as reduced grain size and surface roughness, thus enable highly efficient PeLEDs with an external quantum efficiency of 15.6 %. Our results provide new fundamental insights into the role of organic molecular passivators in boosting the performance of PeLEDs.

Akriti, Enzheng, and Stephen’s paper on Layer-by-Layer Anionic Diffusion in Two-Dimensional Halide Perovskite Vertical Heterostructures has been published in Nature Nanotechnology. Big congratulations!

Anionic diffusion in a soft crystal lattice of hybrid halide perovskites affects their stability, optoelectronic properties and the resulting device performance. The use of two-dimensional (2D) halide perovskites improves the chemical stability of perovskites and suppresses the intrinsic anionic diffusion in solid-state devices. However, a fundamental understanding of the role of organic cations in inhibiting anionic diffusion across the perovskite–ligand interface is missing. Here we demonstrate the first quantitative investigation of the anionic interdiffusion across atomically flat 2D vertical heterojunctions. A ‘quantized’ layer-by-layer diffusion model is proposed to describe the behaviour of the anionic migration in 2D halide perovskites. Our results provide important insights into the mechanism of anionic diffusion in 2D perovskites and provide a new materials platform with an enhanced stability for heterostructure integration.

This is is highlighted in Purdue Chemical Engineering newsroom, and many media.

Ke’s paper on Organic Cation Engineering for Vertical Charge Transport in Lead-Free Perovskite Quantum Wells has been published in Small Science. Congratulations! Read the story here.

Jee passes his qualifier exam and now becomes a PhD candidate. Congratulations!

Blake’s work on skin-inspired mechanically self-healing perovskite solar cells has been published in Cell Reports Physical Science. Congratulations! Read the story here.

We are guest editing a special issue of “Halide Perovskites for Photonics and Optoelectronics” in Optical Materials Express together with Prof. Xiwen Gong @ University of Michigan, USA; Prof. Sergey Makarov @ ITMO University, Russia; Prof. Barry Rand @ Princeton University, USA; and Prof. Yongsheng Zhao @ Institute of Chemistry, CAS, China. Looking forward to your submissions!