Mr. Ross Haroldson Profile

Ross Haroldson

at Univ of Texas at Dallas

SPIE Involvement:

Author

Publications (3)

Proceedings Article | 20 August 2020 Poster + Presentation + Paper

Bright perovskite light-emitting electrochemical cell utilizing CNT sheets as a tunable charge injector

Masoud Alahbakhshi, Alexios Papadimitratos, Ross Haroldson, Aditya Mishra, Artur Ishteev, Josef Velten, Qing Gu, Jason Slinker, Anvar Zakhidov

Proceedings Volume 11473, 114731N (2020) https://doi.org/10.1117/12.2567751

KEYWORDS: Perovskite, Electrodes, Lithium, Ions, Carbon nanotubes, Cesium, Thin films, Electroluminescence, Doping, LED lighting

Read Abstract +

Proceedings Article | 26 February 2020 Presentation + Paper

Visible frequency active hyperbolic metamaterials

Zhitong Li, Joseph S. Smalley, Ross Haroldson, Dayang Lin, Roberta Hawkins, Abouzar Gharajeh, Jiyoung Moon, Junpeng Hou, Chuanwei Zhang, Walter Hu, Anvar Zakhidov, Qing Gu

Proceedings Volume 11289, 112891N (2020) https://doi.org/10.1117/12.2544508

KEYWORDS: Gold, Perovskite, Dielectric polarization, Absorption, Dielectrics, Metamaterials, Metals, Electro optical imaging, Nanoimprint lithography, Visible radiation

Read Abstract +

Proceedings Article | 16 June 2017 Presentation

Carbon nanotube charge collectors for nanoimprinted hybrid perovskite photovoltaics (Conference Presentation)

Anvar Zakhidov, Ross Haroldson, Danila Saranin, Patricia Martinez, Artur Ishteev

Proceedings Volume 10248, 102480M (2017) https://doi.org/10.1117/12.2267057

KEYWORDS: Perovskite, Interfaces, Spectroscopy, Solar cells, Excitons, Diffusion, Carbon nanotubes, Photovoltaics, Crystals, Semiconductors

Read Abstract +

The hybrid (organo-inorganic) lead-halide perovskites revolutionized the field of solar cell research due to the impressive power conversion efficiencies of up to 21% recently reported in perovskite based solar cells. This talk will present first the general concepts of excitonic photovoltaics, as compared to conventional Si-type solar cells, asking a question: is hybrid perovskite PV an excitonic solar cell or not? Do we need excitons dissociation at D-A interfaces or CNT charge collectors? Then I will show our recent experimental results on the fast spectroscopy of excitons, magnetic field effect on generation of correlated (e-h) pairs. Also will discuss our Hall effect results, that allows to evaluate intrinsic charge carrier transport and direct measurements of mobility in these materials performed for the first time in steady-state dc transport regime. From these measurements, we have obtained the electron-hole recombination coefficient, the carrier diffusion length and lifetime. Our main results include the intrinsic Hall carrier mobility reaching up to 60 cm2V-1s^-1 in perovskite single crystals, carrier lifetimes of up to 3 ms (surprisingly too long!), and carrier diffusion lengths as long as 650 μm (huge if compared to organic and even best inorganic materials). Our results also demonstrate that photocarrier recombination in these disordered solution-processed perovskites is as weak as in the best (high-purity single crystals) of conventional direct-band inorganic semiconductors. Moreover, as we show in our experiment, carrier trapping in perovskites is also strongly suppressed, which accounts for such long carrier lifetimes and diffusion lengths, significantly longer than similar parameters in the best inorganic semiconductors, such e.g. as GaAs. All these remarkable transport properties of hybrid perovskites need to be understood from fundamental physics point of view. Looks like we need some new concepts to explain the mysterious properties of “protected” hybrid perovskites. We suggest that some of this unusual properties can be attributed to a special type of “dipole rotational polaron” formed in their lattice due to interactions of charge with methyl-ammonium organic dipoles, each of 2.3 Debye. Examples of perovskite solar cell with transparent CNT charge collectors will demonstrated the 3 D charge collection in the monolithic tandems of perovskite PV with other dissimilar materials PVs, such as OPV and inorganic PV. We describe the pioneering methods to create highly transparent CNT sheets by dry lamination from vertically alligned CVD forests of MWCNTs. Transparency can be further increased by converting CNT aerogels into locally collapsed meshs with micron scale oppenings by spraying Ag nanowires, which lowers sheet resistance to values of Rsh< 40 ohm/sq. such AgNW@CNT transparent sheets are ideal interlayers in three terminal tandems of perovskite PV with polymeric OPV and/or inorganic solar cells. We show that nanoimprinting can further improve the performance of perovskite photodetectors and optoelectronic devices

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years