Band energy diagrams of n-GaInP/n-AlInP(100) surfaces and heterointerfaces studied by X-ray photoelectron spectroscopy

Integration of Multijunction Absorbers and Catalysts for Efficient Solar‐Driven Artificial Leaf Structures: A Physical and Materials Science Perspective

“…In search for optimum material combinations for lightinduced unassisted water splitting, both bulk and interface properties are crucial. In principle, III-V semiconductor compounds are capable of providing Fermi-level splitting alias photovoltage close to the theoretical limit, [355,356] sufficient absorption coefficients in relation to the diffusion lengths, [357] and selective charge carrier transport, [45] whereas the interfaces need to exhibit proper energy band alignments, [351] promote carrier transport to the adjacent materials as the liquid electrolyte, prohibit nonradiative recombination, and remain stable. [7] Challenges for a competitive application of III-V semiconductors are manifold: lowering production costs, deep understanding of the elementary processes, integration of Si with III-V epitaxy, new absorber structures such as MQW structures, [84] stability of well-defined hetero-interfaces, etc.…”

“…In search for optimum material combinations for light‐induced unassisted water splitting, both bulk and interface properties are crucial. In principle, III–V semiconductor compounds are capable of providing Fermi‐level splitting alias photovoltage close to the theoretical limit, [ 355,356 ] sufficient absorption coefficients in relation to the diffusion lengths, [ 357 ] and selective charge carrier transport, [ 45 ] whereas the interfaces need to exhibit proper energy band alignments, [ 351 ] promote carrier transport to the adjacent materials as the liquid electrolyte, prohibit nonradiative recombination, and remain stable. [ 7 ]…”

“…[17,31,252] Even at this model-like junction, characterization of the band alignment, band offsets, the influence of defects, interdiffusion, or the preparation of a well-defined, atomically abrupt interface is nevertheless a challenge. [351] Currently, monolithic solar cells with highest conversion efficiencies (47.6% under light concentration) have been achieved with a multijunction cell with four individual absorber structures connected in series: [17,352,353] a GaAs(100)-based tandem solar cell (Ga 0.5 In 0.49 P/GaAs with bandgaps of 1.88/1.42 eV) on top bonded to a bottom InP(100)-based tandem (Ga 0.16 In 0.84 As 0.31 P 0.69 /Ga 0.47 In 0.53 As with 1.12/0.72 eV). This configuration is close to the perfect bandgap combination for a four-junction device.…”

Unraveling Electron Dynamics in p-type Indium Phosphide (100): A Time-Resolved Two-Photon Photoemission Study

“…To date, III–V semiconductors have demonstrated the highest solar-to-hydrogen conversion efficiencies. , Their direct band gaps, high electron mobilities, and low exciton binding energies in combination with good surface- and band gap tunability make them highly attractive for PEC and PV applications. In our study, we focus on InP(100) as a reference material among P-containing III–V semiconductors such as GaP, GaInP, or AlInP, which all display analogous surface reconstructions. − InP is a well-established semiconductor used for PEC ,− with various known surface reconstructions. Under PEC operating conditions using an aqueous electrolyte, the choice of InP surface reconstruction influences its surface electronic energy levels, surface charge carrier lifetimes and stability, and thus its overall performance. − For InP(100), depending on the chemical potentials of P and H 2 , typically two surface reconstructions are possible: (i) the phosphorus-terminated “P-rich” p(2 × 2)/c(4 × 2) surface reconstruction consists of buckled P–P dimers stabilized by one H atom each. , The H atom is required to satisfy the electron counting principle predicted by Hahn and Schmidt , and verified experimentally in several studies. ,, The adjacent buckled phosphorus dimer rows can be arranged in-phase, forming a p(2 × 2) surface reconstruction, or out-of-phase, forming a c(4 × 2) surface reconstruction.…”

“…States 2,3,4,5,6, and 8 exhibit a scaling factor of 1.0 ± 0.2 between photon and electron energy, suggesting that they are intermediate, normally unoccupied states populated with electrons pumped from filled valence band states. 3 State 7 shows an intermediate scaling factor of 1.4 ± 0.1.…”