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NSTC/CREOL Joint Speaker Series: "The emergence of hybrid-perovskites for low-cost, high-efficiency optoelectronic devices" by Aditya D. Mohite

Friday, March 31, 2017 11:00 AM to 12:00 PM
CREOL Room 103

Aditya D. Mohite
Material Synthesis and Integrated Devices
Los Alamos National Laboratory

Abstract:

Hybrid (inorganic-­-organic) perovskites have demonstrated an extraordinary potential for clean  sustainable  energy  technologies  and  low-­-cost  optoelectronic  devices  such  as  solar  cells; light emitting diodes, detectors, sensors, ionic conductors etc. In spite of the unprecedented  progress  in  the  past  six  years,  one  of  the  key  challenges  that  exist  in  the  field today is the large degree of processing dependent variability in the structural and physical  properties.  This  has  limited  the  access  to  the  intrinsic  properties  of  hybrid  perovskites and led to to multiple interpretations of experimental data. In addition to this, the stability and reliability of devices has also been strongly affected and remains an open question,  which  might  determine  the  fate  of  this  remarkable  material  despite  excellent  properties. In this talk, I will describe our recently discovered approach for thin-­-film crystal  growth  as  a  general  strategy  for  growing  highly  crystalline,  bulk-­-like  thin-­-films  of  both three-­-dimensional (3D) and layered two-­-dimensional (2D) hybrid perovskites that overcomes the above issues by allowing access to the intrinsic charge and energy transport processes  within  the  perovskite  thin-­-films  and  results  in  reproducible  and  stable  high  performance optoelectronic devices.

Briefly,  photovoltaic  devices  fabricated  using  3D  hybrid  perovskites  show  hysteresis-­-free  response, with high degree of reproducibility, with an average efficiency of planar devices approaching  ~18%.  Photo-­-physical,  electrical  characterization  and  theoretical  modeling  attribute the improved performance to reduced defects (bulk and interface) and improved charge-­-carrier  mobility  in  large-­-grain  devices.  Furthermore,  our  most  recent  efforts  on  understanding and controlling photo-­-degradation in these systems demonstrate that the large  grain-­-size  perovskite  thin-­-films  are  not  limited  by  detrimental  effects  such  as  ion  migration or defect assisted trapping generally reported for perovskite thin-­-film devices allowing us to probe true photo-­-physical processes that lead to the degradation of PCE in perovskite solar cells and control the light-­-induced degradation in these materials.

Finally,  I will also describe some new results on Ruddlesden-­-Popper phase perovskites based devices. In our first few attempts, we fabricated solar cells with efficiency approaching 13% as compared to the previous best of 4.5%. This phenomenal increase in efficiency is attributed to the near single-­-crystalline  quality thin-­-films with a strongly preferential out-­-of-­-plane alignment of the inorganic perovskite component that facilitates efficient  charge  transport.  Photovoltaic devices exhibit no hysteresis or degradation in performance under continuous operation and withstand an illumination intensity up to 4-­-Suns. Importantly, these devices with layered perovskites exhibit extraordinary, technologically relevant stability with no loss in performance with for ~2000 hours under humidity and 1-SUN full spectrum illumination.

Biography:

Aditya Mohite is the PI of the Light-­-to-­-Energy team and directs an energy and optoelectronic devices lab working on understanding and controlling charge and energy transfer processes occurring at interfaces created with organic and inorganic materials  for  thin-­-film clean energy technologies. His research philosophy is applying creative and  “out-­-of-­-the-­-box” approaches to solve fundamental scientific bottlenecks and demonstrate technologically relevant performance in devices that is on par or exceeds the current state-­-of-­-the-­-art devices.  

He has published more than 80 peer reviewed papers in journals such as Science, Nature, Nature Materials, Nature Nanotechnology, Nano Letters, ACS Nano, Chemical Society Reviews, Applied Physics Letters and Advanced Materials amongst others. He has also delivered more than 50 invited talks.

For additional information:

Dr. Jayan Thomas
Jayan.Thomas@ucf.edu

 

 

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