Novel Solar Cell Materials: Insights from First-Principles

Abstract

Although silicon solar cells currently dominate the market share for photovoltaic (PV) devices, it is important to explore other materials and device configurations that could be cheaper and more environmentally friendly to produce, as well as potentially more efficient at energy conversion. Here, we review some of our recent theoretical work aimed at accurate evaluation of key materials properties associated with optimizing alternative PV materials. These include potential new light absorbers and transparent conductors in devices ranging from traditional PVs to tandem dye-sensitized solar cells and thin-film PVs to intermediate band gap PVs. We specifically focus on two materials families: transition-metal oxides (TMOs), such as NiO, CoO, FeO, and Cu 2 O, and mixed metal sulfides, such as Cu 2 ZnSnS 4 . Both families are p-type semiconductors being explored as less expensive solar cell components.

A First‐Principles‐Based Sub‐Lattice Formalism for Predicting Off‐Stoichiometry in Materials for Solar Thermochemical Applications: The Example of Ceria

“…Many energy-relevant materials exhibit off-stoichiometric compositions. [1][2][3][4][5][6][7][8] For example, most electrodes in intercalation DOI: 10.1002/adts.202000112 batteries [9][10][11][12][13] and semiconductors in nonsilicon photovoltaics [14][15][16][17] exhibit vacancies and/or other point defects in at least one set of sites (or a sub-lattice) within their structure. Other materials are off-stoichiometric in their equilibrium bulk form, such as FeO (wüstite), which exhibits ≈5-10% Fe-vacancies at room temperature.…”

Transition Metal-Hyperdoped InP Semiconductors as Efficient Solar Absorber Materials

“…However, the Cr@InP material yielded a host bandgap and sub-bandgap values that were far from those ideal values; a theoretical efficiency~60% would be obtained based on its electronic structure [14][15][16]. This value still led to a considerable improvement with respect to the theoretical maximum conversion efficiency of~33% based on the SQ model [13].…”

“…Unfortunately, even the most efficient InP solar cells have only reached efficiencies up to 22.1% [9][10][11][12]. Consequently, its efficiency as a solar cell material must be improved to reach up to (or even over) the theoretical maximum conversion efficiency~33% based on the Shockley-Queisser (SQ) model [13].Among the alternative designs that, theoretically, can exceed the SQ limit, large efforts have been made based on the in-gap band (IGB) concept. Those materials with an IGB (also known as an intermediate band) own a partially filled narrow band located between the valence and conduction bands (VB and CB, respectively) of the host semiconductor (see Figure 1).…”

“…Unfortunately, even the most efficient InP solar cells have only reached efficiencies up to 22.1% [9][10][11][12]. Consequently, its efficiency as a solar cell material must be improved to reach up to (or even over) the theoretical maximum conversion efficiency~33% based on the Shockley-Queisser (SQ) model [13].…”

Multiscale modeling of silicon heterojunction solar cells

“…This necessitates the use of atomistic and first principle approaches [93] while trying to understand the properties of new materials or quantum phenomena that occur in novel nanostructured devices. Methods such as non-equilibrium Green's functions (NEGF) [94] and full band Monte Carlo [95] are often utilized to study quantum transport in nanostructured devices; however such approaches are computationally very expensive.…”