Effects of Temperature on Excited-State Descriptions of Luminescent Photoelectrochemical Cells Employing Tellrium-Doped Cadmium Sulfide Electrodes.

The effect of temperature on excited-state deactivation processes in a single-crystal, n-type, 100 ppm CdSTe-based photoelectrochemical cell PEC employing aqueous polychalcogenide electrolytes is discussed. While serving as electrodes these materials emit lambda sub max is about 600 nm. Photocurrent quantum yield Thi sub x from ultraband gap greater than or approx. 2.4 eV greater than or approx. 500 nm 501.7 nm excitation increases modestly by less than 20 between 20 degrees and is 100 C degrees photocurrent from band gap edge 514.5 nm excitation increases by about an order of magnitude, reaching is approx. 50-100 of the room temperature 501.7 nm value. Highlighting the competitive nature of emission and photocurrent as excited -state decay processes, luminescence quantum yield Thi sub R declines over the same temperature regime by factors of between 10 and 30. At most, modest red shifts of Lambda sub Max less than 10 nm are observed in the spectral distribution of emission with temperature. These effects are discussed in terms of optical penetration depth, band bending, and the known red shift of the CdS absorption edge with temperature. Correlations involving Thi sub x and Thi sub r suggested by the data are discussed.