Origin Of Photocurrent Research Articles

Solar Energy Conversion through Thylakoid Membranes Wired by Osmium Redox Polymer and Indium Tin Oxide Nanoparticles.

For several decades, much attention has been paid to thylakoid membranes (TMs) as photocatalysts for converting solar light to electricity. Despite extensive research, current technology provides only limited photocurrents. Here, a novel method based on TM-composite material was developed for achieving high photocurrent. When a thin film composed of TMs, osmium redox polymer (Os-RP), and indium tin oxide nanoparticles (ITOnp) was formed on a porous graphite surface, appreciable photocurrent as high as 0.5 mA cm-2 was achieved at 0.4 V vs. Ag/AgCl. Each component plays its own role in transferring electrons from TMs to the anode, resulting in sharp drop in photocurrent with missing any component. Optimization between these three components showed 1 : 0.5 : 30 (TM/Os-RP/ITOnp) was the best ratio. Action spectra confirmed that TMs was the origin of photocurrent. It was inferred from blocking experiments using 3-(3,4-dichlorophenyl)-1,1-dimethylurea as an inhibitor that about 41 % of photocurrent was transferred from QA in photosystem II to the electrode via Os-RP and ITOnp. Quantum efficiencies at 430 and 660 nm were 12.2 and 18.5 %, respectively. Turnover frequency for water oxidation depended upon the amount of the composite. A complete cell with Pt/C cathode produced Pmax of 122 μW cm-2 at 758 μA cm-2 under one sun illumination, which is the highest power density to our knowledge. This study opened a possibility of using TMs as photocatalysts for solar energy conversion.

On the Origin of Photocurrents in Pristine Graphene

Recently Ma et al. (Nature Nanotech. 14, 145, 2019) reported an intrinsic photocurrent in graphene, which occurs as the authors believe “in a different parameter regime from all the previously observed photothermoelectric or photovoltaic photocurrents in graphene”. Here we present an alternative – obvious and transparent explanation of such experiments. We demonstrate that the photo effect occurs in the p–n junctions formed in graphene samples containing two regions of different widths with different particle concentrations. This difference in concentration for various sample widths is found to result from edge doping of samples.

Origin of Photocurrent and Voltage Losses in Organic Solar Cells

AbstractOrganic solar cells (OSCs) have recently achieved power conversion efficiencies (PCEs) of over 16%. However, there still exist large losses in photocurrent and/or voltage in state‐of‐the‐art OSCs, making the PCEs still far below those of inorganic counterparts. Here, the factors and electronic processes for photocurrent and voltage losses are identified and discussed in the framework of device physics and photophysics. To simultaneously obtain both high photocurrent density and low voltage loss toward 20% PCEs, it is crucial to suppress the non‐radiative (NR) recombination of the lowest charge‐transfer (CT) state at the donor–acceptor interface. In principle, theoretical simulations can provide molecular insight into the origin of these losses, which is essential to guide material design. In particular, the authors highlight the importance of the local interface morphologies and the vibronic couplings on suppressing the NR decay of the lowest CT state according to recent theoretical studies.

Origin of Photocurrent in Fullerene-Based Solar Cells

Fullerene-based organic solar cells with only a minute amount of donor show a substantial photocurrent while maintaining a large open-circuit voltage. At low concentrations the donor is fully dispe...

Photoelectrochemistry at transparent SnO 2 electrodes: supersensitization in Nafion® films by mono- and dinuclear ruthenium(II) complexes with hydroquinone

The photoelectrochemical (PEC) behaviour of mono- and dinuclear complexes, [Ru(tap) 3] 2+ (tap = 1,4,5,8-tetraazaphenanthrene) and [Ru(phen) 2] 2hat 4+ (phen = 1,10-phenanthroline; hat = 1,4,5,8,9,12-hexaazatriphenylene), incorporated in recast Nafion® on an SnO 2 electrode, in contact with an aqueous solution containing a reducing agent such as hydroquinone (H 2Q), is examined by two PEC methods: continuous and pulsed laser excitation. The PEC results combined with luminescence lifetime data obtained by diffuse reflectance from recast Nafion®, lead to the evaluation of the quenching rate constant of the excited complex by H 2Q in this medium. The luminescence inhibition by electron transfer from H 2Q to the excited complex produces the reduced complex to which electroactivity is attributed, i.e. the origin of photocurrent and photopotential, and which has a lifetime in the ms time domain in the polyelectrolyte. Other explanations for such long electroactive intermediates are also proposed.

Local origin of photocurrent in semiconductor superlattices.

To trace the origin of photocurrent (PC) in semiconductor superlatices, we have studied the PC spectra as a function of the applied electric field in a novel compositionally graded superlattice, where each well produces a separate peak. The sample consisted of 15 quasiperiods of 40/20-A\r{} ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As/${\mathrm{Al}}_{\mathit{y}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{y}}$As [x=0.03(n-1), y=x+0.3, and (n=1,...,15)]. We show that the PC is due to the transport of electrons with no significant contribution from the holes. At low electric field, when the transport is very slow, the PC originates from a few wells close to the substrate, thus providing local information, unlike optical absorption. As the field increases the active region expands and finally covers the whole superlattice.

On three hypotheses in photo-polarography

Three hypotheses for the origin of photocurrents at electrodes are compared, and types of critical distinguishing experiments are suggested.