Dynamics of photoconversion processes: The energetic cost of lifetime gain in photosynthetic and photovoltaic systems
File(s)
Author(s)
Godin, R
Durrant, J
Type
Journal Article
Abstract
The continued development of solar energy conversion technologies relies on improved understanding of their limitations. In this review, we focus on a comparison of charge carrier dynamics underlying the function of photovoltaic devices with those of both natural and artificial photosynthetic systems. The efficiency of solar energy conversion is the product of the rate of generation of high energy species (charges for solar cells, chemical fuels for photosynthesis) and the energy contained in these species. It is known that the underlying kinetics of the photophysical and charge transfer processes affects the yield of high energy species. Comparatively little attention has been paid to how these kinetics are linked to the energy contained in the high energy species or the energy lost in driving the forward reactions. Here we review the operational parameters of both photovoltaic and photosynthetic systems to highlight the energy cost of extending the lifetime of charge carriers to levels that enable function. We show a strong correlation between the energy lost within the device and the necessary lifetime gain, even when considering natural photosynthesis alongside artificial systems. From consideration of experimental data across all these systems, the emprical energetic cost of each 10 fold increase in lifetime gain is 87 meV. This energetic cost of lifetime gain is approx. 50% greater than the 59 meV predicted from a simple kinetic model. Broadly speaking, photovoltaic devices show smaller energy losses compared to photosynthetic devices due to smaller necessary lifetime gains needed. This is because of faster charge extraction processes in photovoltaic devices compared to the complex multi-electron, multi-proton reactions to produce fuels by photosynthetic devices. The result is that in photosynthetic systems, larger energetic costs are paid to overcome unfavorable kinetic competition between the excited state lifetime and the rate of interfacial reactions. We apply this framework to leading examples of photovoltaic and photosynthetic devices to identify kinetic sources of energy loss and identify possible strategies to reduce this energy loss. The kinetic and energetic analyses undertaken are applicable to both photovoltaic and photosynthetic systems allowing for a holistic comparison both types of solar energy conversion approaches.
Online Publication Date
2022-11-16T00:01:34Z
Date Acceptance
2021-10-21
ISSN
0306-0012
Publisher
Royal Society of Chemistry
Start Page
13372
End Page
13409
Journal / Book Title
Chemical Society Reviews
Volume
50
Issue
23
Copyright Statement
This journal is © The Royal Society of Chemistry 2021
Sponsor
Engineering and Physical Sciences Research Council
Identifier
https://pubs.rsc.org/en/content/articlelanding/2021/CS/D1CS00577D
Grant Number
EP/P032591/1
Subjects
Science & Technology
Physical Sciences
Chemistry, Multidisciplinary
Chemistry
SENSITIZED SOLAR-CELLS
ELECTRON-TRANSFER PROCESSES
CHARGE-CARRIER DYNAMICS
OPEN-CIRCUIT VOLTAGE
TRANSIENT ABSORPTION-SPECTROSCOPY
PARTICULATE PHOTOCATALYST SHEETS
METAL-OXIDE PHOTOELECTRODES
NANOCRYSTALLINE TIO2 FILMS
EXCITON BINDING-ENERGY
VISIBLE-LIGHT-DRIVEN
Electrons
Oxidation-Reduction
Photosynthesis
Protons
Solar Energy
General Chemistry
03 Chemical Sciences
Publication Status
Published
Date Publish Online
2021-11-17