TY  - JOUR
A1  - Crovetto, Andrea
A1  - Hempel, Hannes
A1  - Rusu, Marin
A1  - Choubrac, Leo
A1  - Kojda, Sandrino Danny
A1  - Habicht, Klaus
A1  - Unold, Thomas
T1  - Water adsorption enhances electrical conductivity in transparent p-type CuI
JF  - ACS applied materials & interfaces
N2  - CuI has been recently rediscovered as a p-type transparent conductor with a high figure of merit. Even though many metal iodides are hygroscopic, the effect of moisture on the electrical properties of CuI has not been clarified. In this work, we observe a 2-fold increase in the conductivity of CuI after exposure to ambient humidity for 5 h, followed by slight long-term degradation. Simultaneously, the work function of CuI decreases by almost 1 eV, which can explain the large spread in the previously reported work function values. The conductivity increase is partially reversible and is maximized at intermediate humidity levels. On the basis of the large intragrain mobility measured by THz spectroscopy, we suggest that hydration of grain boundaries may be beneficial for the overall hole mobility.
KW  - transparent conductors
KW  - CuI
KW  - copper iodide
KW  - conductivity
KW  - humidity
KW  - p-type
KW  - work function
Y1  - 2020
U6  - https://doi.org/10.1021/acsami.0c11040
SN  - 1944-8244
SN  - 1944-8252
VL  - 12
IS  - 43
SP  - 48741
EP  - 48747
PB  - American Chemical Society
CY  - Washington, DC
ER  - 
TY  - JOUR
A1  - Le Corre, Vincent M.
A1  - Stolterfoht, Martin
A1  - Perdigón-Toro, Lorena
A1  - Feuerstein, Markus
A1  - Wolff, Christian Michael
A1  - Gil-Escrig, Lidon
A1  - Bolink, Henk J.
A1  - Neher, Dieter
A1  - Koster, L. Jan Anton
T1  - Charge Transport Layers Limiting the Efficiency of Perovskite Solar Cells: How To Optimize Conductivity, Doping, and Thickness
JF  - ACS Applied Energy Materials
N2  - Perovskite solar cells (PSCs) are one of the main research topics of the photovoltaic community; with efficiencies now reaching up to 24%, PSCs are on the way to catching up with classical inorganic solar cells. However, PSCs have not yet reached their full potential. In fact, their efficiency is still limited by nonradiative recombination, mainly via trap-states and by losses due to the poor transport properties of the commonly used transport layers (TLs). Indeed, state-of-the-art TLs (especially if organic) suffer from rather low mobilities, typically within 10(-5) and 10(-2) cm(-2) V-1 s(-1), when compared to the high mobilities, 1-10 cm(-2) V-1 s(-1), measured for perovskites. This work presents a comprehensive analysis of the effect of the mobility, thickness, and doping density of the transport layers based on combined experimental and modeling results of two sets of devices made of a solution-processed high-performing triple-cation (PCE approximate to 20%). The results are also cross-checked on vacuum-processed MAPbI(3) devices. From this analysis, general guidelines on how to optimize a TL are introduced and especially a new and simple formula to easily calculate the amount of doping necessary to counterbalance the low mobility of the TLs.
KW  - perovskite solar cells
KW  - transport layers
KW  - conductivity
KW  - doping
KW  - charge transport
Y1  - 2019
U6  - https://doi.org/10.1021/acsaem.9b00856
SN  - 2574-0962
VL  - 2
IS  - 9
SP  - 6280
EP  - 6287
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Pingel, Patrick
A1  - Arvind, Malavika
A1  - Kölln, Lisa
A1  - Steyrleuthner, Robert
A1  - Kraffert, Felix
A1  - Behrends, Jan
A1  - Janietz, Silvia
A1  - Neher, Dieter
T1  - p-Type Doping of Poly(3-hexylthiophene) with the Strong Lewis Acid Tris(pentafluorophenyl)borane
JF  - Advanced electronic materials
N2  - State-of-the-art p-type doping of organic semiconductors is usually achieved by employing strong -electron acceptors, a prominent example being tetrafluorotetracyanoquinodimethane (F(4)TCNQ). Here, doping of the semiconducting model polymer poly(3-hexylthiophene), P3HT, using the strong Lewis acid tris(pentafluorophenyl)borane (BCF) as a dopant, is investigated by admittance, conductivity, and electron paramagnetic resonance measurements. The electrical characteristics of BCF- and F(4)TCNQ-doped P3HT layers are shown to be very similar in terms of the mobile hole density and the doping efficiency. Roughly 18% of the employed dopants create mobile holes in either F-4 TCNQ- or BCF-doped P3HT, while the majority of doping-induced holes remain strongly Coulomb-bound to the dopant anions. Despite similar hole densities, conductivity and hole mobility are higher in BCF-doped P3HT layers than in F(4)TCNQ-doped samples. This and the good solubility in many organic solvents render BCF very useful for p-type doping of organic semiconductors.
KW  - charge carrier transport
KW  - charge transfer
KW  - conductivity
KW  - molecular doping
KW  - organic semiconductors
Y1  - 2016
U6  - https://doi.org/10.1002/aelm.201600204
SN  - 2199-160X
VL  - 2
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -