Tandem PEC photocathode, GaInP/GaInAs 1.78 / 1.26 eV (Cheng 2018)

The eight checks evaluated for this variant's own data and bounds on the shared route (the route page shows the parent's).

Measured or reported performance

1. solar-to-hydrogen efficiency (acidic electrolyte)19.3%device2018
   hydrogen free-energy output over incident simulated AM 1.5G solar power, unassisted; monolithic Ga₀.₄₁In₀.₅₉P / Ga₀.₈₉In₀.₁₁As tandem photocathode (1.78 / 1.26 eV) with a crystalline TiO₂ interlayer and Rh nanoparticle catalyst, acidic perchlorate electrolyte, the initial efficiency; the authors place it at 0.85 of the 22.8 % theoretical limit for this gap combination
   basis: PEC water splitting, dual-junction absorber, AM1.5G
   conversion-efficiency · measured · refs [1]
2. solar-to-hydrogen efficiency (neutral electrolyte)18.5%device2018
   the same device in a buffered solution at pH 7, unassisted, under simulated AM 1.5G
   basis: PEC water splitting, dual-junction absorber, AM1.5G
   conversion-efficiency · measured · refs [1]

best recorded efficiency (derived)

19.3% — solar-to-hydrogen efficiency (acidic electrolyte), device, 2018; derived from the structured data above, not a stored number

Bounds recorded for this exact architecture

Limits valid only for this architecture (pass 42), evaluated beside the route's generic bounds in the thermodynamic-bound check above; they never reach the generic route.

• Theoretical STH limit for the GaInP/GaInAs 1.78 / 1.26 eV tandem (Cheng 2018) · upper-bound
  η_STH ≤ 22.8 % for the 1.78 eV / 1.26 eV GaInP/GaInAs dual-junction photocathode under AM1.5G, assuming 100 % above-bandgap absorption and 100 % external radiative efficiency (catalytic exchange current densities {1, 10⁻³} mA cm⁻², R_S = 0, R_SH = ∞)
  the limit is computed for exactly this gap pair, 1.78 eV / 1.26 eV, in the SQwater framework; the global dual-junction maximum (40.0 % at 0.52 / 1.40 eV) reaches the same route through the phenomenon — the first architecture-specific bound in the atlas: it lives here and never on the generic photoelectrochemical route · refs [1] [2]

Steps (the parent's exact sequence)

1. Incident radiation flux → Photoelectrochemical effect
2. Photoelectrochemical effect → Chemical fuel

Every step, its conditions and its evidence are on the route page.

Evidence for this variant

1. [1]
   W.-H. Cheng et al.. Monolithic Photoelectrochemical Device for Direct Water Splitting with 19% Efficiency (2018)

   ACS Energy Letters 3, 1795–1800 · doi:10.1021/acsenergylett.8b00920 · record
2. [2]
   Katherine T. Fountaine, Hans Joachim Lewerenz, Harry A. Atwater. Efficiency limits for photoelectrochemical water-splitting (2016)

   Nature Communications 7, 13706 (open access) · doi:10.1038/ncomms13706 · record