Feng Gao: High-performance perovskite optoelectronic devices enabled by additives

Friday 6 December 2019 14:00 - 15:00
k-space
Published 2019-11-25 16:03 by David Alcer

Assoc. Prof. Feng Gao from Linköping University will visit us next Friday to give a presentation about “High-performance perovskite optoelectronic devices enabled by additives” during the optics meeting, scheduled at 14:00 on Friday, December 6 in k-space. We invite you to attend the meeting and listen to his presentation. The abstract is found below.


High-performance perovskite optoelectronic devices enabled by additives

Optoelectronic devices based on metal halide perovskites have developed very quickly during the past ten years. One of the important strategies to boost the performance is the employment of additives. In this talk, I will give two examples where the additives significantly improve the stability of perovskite solar cells and enhance the efficiency of perovskite light-emitting diodes (LEDs).
For perovskite solar cells, ion migration in the perovskite active layer, especially under light illumination and heat, is arguably the most difficult aspect to mitigate. We incorporate ionic liquids into the perovskite film, and demonstrate both a notable increase in efficiency and remarkable enhancement in long-term stability. We observe ~ 5% degradation of encapsulated devices under continuous simulated full-spectrum sunlight for over 1,800 hours at an elevated temperature of ~ 70 to 75 ˚C and estimate a T80 lifetime (time to 80% of its peak performance) of ~ 5,200 hours. 1
For perovskite LEDs, a major efficiency limit is trap-mediated non-radiative losses. Defect passivation using organic molecules has been identified as an attractive approach to tackle this issue. However, implementation of this approach has been hindered by a lack of deep understanding of how the molecular structures affect the passivation effectiveness. We reveal synergistic effect of precursor stoichiometry and interfacial reactions for perovskite LEDs.2 We show that hydrogen bonds play a critical role in affecting the passivation. By weakening the hydrogen bonding between the passivating functional moieties and the organic cation featuring the perovskite, we significantly enhance the interaction with defects sites and minimize non-radiative recombination losses. Consequently, we achieve exceptionally high-performance near infrared perovskite LEDs with a high external quantum efficiency (EQE) over 20%.3 In addition, we also demonstrate the potential of our high-efficiency perovskite LEDs in optical communications and biomedicine diagnosis applications.4

1, S. Bai, et al. Nature, 571, 245 (2019)
2, Z. Yuan, et al. Nature Communications, 10, 2818 (2019)
3, W. Xu, et al. Nature Photonics, 13, 418 (2019)
4, C. Bao, et al, Nature Electronics, under review (2019)