TY  - JOUR
A1  - Hempel, Hannes
A1  - Savenjie, Tom J.
A1  - Stolterfoht, Martin
A1  - Neu, Jens
A1  - Failla, Michele
A1  - Paingad, Vaisakh C.
A1  - Kužel, Petr
A1  - Heilweil, Edwin J.
A1  - Spies, Jacob A.
A1  - Schleuning, Markus
A1  - Zhao, Jiashang
A1  - Friedrich, Dennis
A1  - Schwarzburg, Klaus
A1  - Siebbeles, Laurens D. A.
A1  - Dörflinger, Patrick
A1  - Dyakonov, Vladimir
A1  - Katoh, Ryuzi
A1  - Hong, Min Ji
A1  - Labram, John G.
A1  - Monti, Maurizio
A1  - Butler-Caddle, Edward
A1  - Lloyd-Hughes, James
A1  - Taheri, Mohammad M.
A1  - Baxter, Jason B.
A1  - Magnanelli, Timothy J.
A1  - Luo, Simon
A1  - Cardon, Joseph M.
A1  - Ardo, Shane
A1  - Unold, Thomas
T1  - Predicting solar cell performance from terahertz and microwave spectroscopy
JF  - Advanced energy materials
N2  - Mobilities and lifetimes of photogenerated charge carriers are core properties of photovoltaic materials and can both be characterized by contactless terahertz or microwave measurements. Here, the expertise from fifteen laboratories is combined to quantitatively model the current-voltage characteristics of a solar cell from such measurements. To this end, the impact of measurement conditions, alternate interpretations, and experimental inter-laboratory variations are discussed using a (Cs,FA,MA)Pb(I,Br)(3) halide perovskite thin-film as a case study. At 1 sun equivalent excitation, neither transport nor recombination is significantly affected by exciton formation or trapping. Terahertz, microwave, and photoluminescence transients for the neat material yield consistent effective lifetimes implying a resistance-free JV-curve with a potential power conversion efficiency of 24.6 %. For grainsizes above approximate to 20 nm, intra-grain charge transport is characterized by terahertz sum mobilities of approximate to 32 cm(2) V-1 s(-1). Drift-diffusion simulations indicate that these intra-grain mobilities can slightly reduce the fill factor of perovskite solar cells to 0.82, in accordance with the best-realized devices in the literature. Beyond perovskites, this work can guide a highly predictive characterization of any emerging semiconductor for photovoltaic or photoelectrochemical energy conversion. A best practice for the interpretation of terahertz and microwave measurements on photovoltaic materials is presented.
KW  - lifetime
KW  - microwaves
KW  - mobility
KW  - solar cells
KW  - terahertz
Y1  - 2022
U6  - https://doi.org/10.1002/aenm.202102776
SN  - 1614-6832
SN  - 1614-6840
VL  - 12
IS  - 13
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Shi, Wenqin
A1  - Eijt, Stephan W. H.
A1  - Sandeep, Chandramathi Sukumaran Suchand
A1  - Siebbeles, Laurens D. A.
A1  - Houtepen, Arjan J.
A1  - Kinge, Sachin
A1  - Bruck, Ekkes
A1  - Barbiellini, Bernardo
A1  - Bansil, Arun
T1  - Ligand-surface interactions and surface oxidation of colloidal PbSe quantum dots revealed by thin-film positron annihilation methods
JF  - Applied physics letters
N2  - Positron Two Dimensional Angular Correlation of Annihilation Radiation (2D-ACAR) measurements reveal modifications of the electronic structure and composition at the surfaces of PbSe quantum dots (QDs), deposited as thin films, produced by various ligands containing either oxygen or nitrogen atoms. In particular, the 2D--ACAR measurements on thin films of colloidal PbSe QDs capped with oleic acid ligands yield an increased intensity in the electron momentum density (EMD) at high momenta compared to PbSe quantum dots capped with oleylamine. Moreover, the EMD of PbSe QDs is strongly affected by the small ethylenediamine ligands, since these molecules lead to small distances between QDs and favor neck formation between near neighbor QDs, inducing electronic coupling between neighboring QDs. The high sensitivity to the presence of oxygen atoms at the surface can be also exploited to monitor the surface oxidation of PbSe QDs upon exposure to air. Our study clearly demonstrates that positron annihilation spectroscopy applied to thin films can probe surface transformations of colloidal semiconductor QDs embedded in functional layers. (C) 2016 AIP Publishing LLC.
Y1  - 2016
U6  - https://doi.org/10.1063/1.4942609
SN  - 0003-6951
SN  - 1077-3118
VL  - 108
SP  - 213
EP  - 230
PB  - American Institute of Physics
CY  - Melville
ER  -