Absorbed photon-to-current efficiency APCE

Fig. 5.60 Absorbed-photon-to-current-efficiency APCE) of Ti-Fe-0 nanotube array samples at (a) 0.5 V bias, and (b) 0.7 V bias.

Ultrafast injection of carriers into the UO2 substrate suggests that overall cell efficiency is not limited by this process but by intervening transfer mechanisms (e.g., trapped state populations reducing quantum yield) or longer time scale electron-dye recombination rates (typically taking microseconds). For example, it was found that the absorbed photon to current efficiency (APCE) is considerably reduced for V compared to IV under identical cell conditions (27,55). While V has a 350 mV lower electrochemical reduction potential than IV (and hence a red-shifted absorption spectrum), it is unclear why the redder absorbing dye (V) does not inject as efficiently (56). Recent visible excitation with broadband... 

Absorbed Photon-to-Current Efficiency (APCE)/ Internal Quantum Efficiency (IQE)... 

PEC device efficiencies as measured by IPCE/EQE or STH implicitly include losses from impinging photons that are reflected or transmitted. To understand the inherent performance of a material, it is often helpful to subtract these losses and measure efficiency based only on photons absorbed. This is known as the absorbed photon-to-current efficiency (APCE), which describes the photocurrent collected per incident photon absorbed. APCE is synonymous with internal quantum efficiency (IQE). This is a particularly useful quantity to measure when studying thin films, since it helps to determine the optimum balance between maximal path-length for photon absorption versus minimal effective e /h" transport distance within the material. 

This required an exact determination of the quantum yield per absorbed photon. Since the absorption of a single QD layer is small, Eq. (9.34) is not useful. The authors defined instead an absorbed photon-to-current efficiency (APCE) determined by... 

IPCE values in excess of 80% for the photo-oxidation of water have been reported for, e.g., WO3 [78] and for Ti02 under UV illumination [79], Another useful parameter is the APCE, or absorbed photon-to-current conversion efficiency. In contrast to the IPCE, the APCE also corrects for reflection losses. Often referred to as the internal quantum efficiency, it is related to the IPCE via... 

APCE Absorbed photon-to-current conversion efficiency... 

Another useful measurement is the spectral response of the cell, the Incident Photon-to-current Conversion Efficiency s (IPCE), given in Equation 3.13, or the Absorbed Photon-to-current Conversion Efficiency (APCE), given in Equation 3.14. 

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