ABSTRACT:
Hybrid solar cells combine inorganic and organic materials to utilise the low cost cell
production of organic photovoltaics (OPV) as well as obtaining other advantages, such
as tuneable absorption spectra and improved environmental stability, from the inorganic
component. The design of the inorganic materials used in hybrid solar cells, particularly
the electronic structure, is crucial to the performance of the device. There exists a tradeoff in electronic structure of the acceptor material in a bulk heterojunction device
between a small band gap, for maximised solar spectrum absorption, and a high lying
Conduction Band edge for maximal open circuit voltage (V
oc). Due to this trade off,
there exists an optimal electronic structure design for an inorganic acceptor. To date,
four major material types have been investigated by researchers, these being CdSe, Si,
metal oxide nanoparticles and low band gap nanoparticles, where CdSe tetrapods
represent the state of the art, yielding a Power Conversion Efficiency (PCE) of ~ 3.2%.
This review compares the electronic structure of these materials with the optimal design
components of an inorganic material. This report provides the reader with a concise
synthesis of the current state of the art for hybrid solar cells and provides a
comprehensive comparison between possible inorganic acceptor materials.