TY  - JOUR
AU  - Ravishankar, Sandheep
AU  - Bisquert, Juan
AU  - Kirchartz, Thomas
TI  - Interpretation of Mott–Schottky plots of photoanodes for water splitting
JO  - Chemical science
VL  - 13
IS  - 17
SN  - 2041-6520
CY  - Cambridge
PB  - RSC
M1  - FZJ-2022-02630
SP  - 4828 - 4837
PY  - 2022
AB  - A large body of literature reports that both bismuth vanadate and haematite photoanodes are semiconductors with an extremely high doping density between 10^18-10^21 cm-3. Such values are obtained from Mott-Schottky plots by assuming that the measured capacitance is dominated by the capacitance of the depletion layer formed by the doping density within the photoanode. In this work, we show that such an assumption is erroneous in many cases because the injection of electrons from the collecting contact creates a ubiquitous capacitance step that is very difficult to distinguish from that of the depletion layer. Based on this reasoning, we derive an analytical resolution limit that is independent of the assumed active area and surface roughness of the photoanode, below which doping densities cannot be measured in a capacitance measurement. We find that the reported doping densities in literature lie very close to this value and therefore conclude that there is no credible evidence from capacitance measurements that confirms that bismuth vanadate and haematite photoanodes contain high doping densities.
LB  - PUB:(DE-HGF)16
C6  - 35655867
UR  - <Go to ISI:>//WOS:000781235700001
DO  - DOI:10.1039/D1SC06401K
UR  - https://juser.fz-juelich.de/record/908477
ER  -