Photoconductive decay lifetime and Suns-Voc diagnostics of efficient heterojunction solar cells
Minority carrier lifetime and Suns-Voc measurements are well-accepted methods for characterization of solar cell devices. We use these methods, with an instrument from Sinton Consulting, as we fabricate and optimize state-of-the-art all hot-wire chemical vapor deposition (HWCVD) silicon heterojunction (SHJ) devices. For double-sided SHJ devices, lifetime measurements were performed immediately after hydrogenated amorphous silicon (a-Si:H) deposition of the front emitter and back base contacts on a Silicon wafer, and also after indium tin oxide (ITO) deposition of transparent conducting oxide contacts. We report results of minority carrier lifetime measurements for double-sided p-type Si heterojunction devices and compare Suns-Voc results to Light I–V measurements on 1-cm2 solar cell devices measured on an AM1.5 calibrated XT-10 solar simulator.
Comparison of ITO, In2O3:Zn and In2O3:H transparent conductive oxides as front electrodes for silicon heterojunction solar cell applications
Abstract In this study, we presented a comparative investigation on the electrical, optical, and structural properties of three types of transparent conductive oxides (TCOs), including tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO) and hydrogen-doped indium oxide (In 2 O 3 :H or IO:H) films. Post-annealing treatment (195 °C, 30 min, and air ambient) was performed to optimize the material characteristics of the TCOs. Further, we evaluated the applications of ITO, IZO and IO:H films in silicon heterojunction (SHJ) solar cells. The effects of material characteristics of TCOs on the device performance were studied. It was found that the ITO films with a low resistivity contributed to the fill factor of the SHJ solar cells, while the IZO films showed obvious advantage in open-circuit voltage of the cells, with the best value of 0.736 V. Comparing with ITO and IZO films, the resulting IO:H films feature both highest carrier mobility (with the best value of 100 cm 2 /V·s) and band gap values after annealing, which contribute to the short-circuit current density of 39.18 mA/cm 2 . The SHJ solar cell with IO:H films as front TCO layer, showed a large scale (153.4 cm 2 ) power conversion efficiency of 21.13%, showing an obvious enhancement compared to the ITO and IZO counterparts.
Calculation of Complex Radiant Heat Load From Surrounding Radiator Surface Temperatures
Abstract A method for calculating the radiant heat exchange between an absorber and individual radiating components in its surroundings is reported. Radiator surface temperatures, ambient and absorber temperatures, and configuration factors for radiating components in the surroundings are used in the customary radiant heat exchange formulae. Simplified methods for calculating or estimating configuration factors for radiators of various shapes solely from angles, subtended at the absorber by the radiators are presented. The method has been verified in the laboratory under controlled conditions and has been used to advantage in the field studies. The method has advantages over the globe therometer method in certain applications.