Absorbed photon-to-current conversion

Absorbed photon-to-current conversion efficiency. A term describing the photocurrent collected per incident photon actually absorbed. It is the IPCE normalized to the IQE. 

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. 

In addition to being bound to T1O2 by carboxylate groups, this triruthenium(II) complex can be bound by peripheral sulfonate groups. These complexes absorb over a very broad range in the visible region of the spectrum, and monochromatic incident photon-to-current conversion efficiencies of over 80% have been observed... 

The external quantiun yield or I PC E (incident photon to current efficiency) is defined as the quotient of the number of incident photons and the number of charge carriers output to the external circuit. It is smaller than the internal quantum yield for conversion of the absorbed photons into charge carriers within the cell, because it takes into account losses due to reflection, recombination, and scattering. In contrast to the internal quantum yield, which can attain values of nearly 100% (see above), the value of the external quantum yield can be measured directly from the short-circuit current density jsc. with jsc = Isc/A where A is the active area of the cell, and the incident light intensity is lo- At a given wavelength k, we have... 

Furthermore, the production is expected to be easily scalable. This technology is currently developed by many researchers around the world, but has not yet reached the marketplace. In order for polymer solar cells to become economic their efficiency must be improved. The power conversion efficiency of a solar cell is dictated by three factors (i) the fraction of sunlight that can be absorbed, (ii) the fraction of absorbed photons that lead to extracted charges ( internal quantum efficiency ), and (iii) the energy that is retained by the extracted charges (ideally close to the open-circuit voltage ). In this review we will refer often to factors (ii) and (ui). Their interplay is not well understood and at present these have not both been optimized simultaneously even in state-of-the-art organic solar cells. 

There have been a few reports of II-VI and III-V heterojunction devices which have approached or even surpassed the performance of silicon cells. p-InP/n-CdS cells with a solar conversion efficiency of 12.5% have been fabricated.84 This good efficiency arises firstly because of the nature of InP the band gap is at 1.34 eV, which is optimal for the solar spectrum, and the transition is direct, so the absorption edge is steep. Secondly, there is an excellent crystal lattice match between InP and CdS, which means that almost fault-free junctions can be grown. p-CuInSe2/n-CdS cells which display current efficiencies (defined as electrons flowing in the short-circuit current per photon absorbed) of up to 70% between 550 and 1250 nm, and solar conversion efficiencies of ca. 5% have been made.85 p-CdTe/n-CdS cells of rather similar performance (current efficiency 85%, solar conversion efficiency 4.0%) have been produced without detailed attention to optimization of cell design, and it has been calculated that p-CdTe/n-ZiiaCdi-aS cells should be capable of a 41 44... 

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