Cell Temperature Coefficients Research Articles

Amorphous/Crystalline Silicon Interface Passivation: Ambient-Temperature Dependence and Implications for Solar Cell Performance

Silicon heterojunction (SHJ) solar cells feature amorphous silicon passivation films, which enable very high voltages. We report how such passivation increases with operating temperature for amorphous silicon stacks involving doped layers and decreases for intrinsic-layer-only passivation. We discuss the implications of this phenomenon on the solar cell's temperature coefficient, which represents an important figure-of-merit for the energy yield of devices deployed in the field. We show evidence that both open-circuit voltage ( V oc) and fill factor (FF) are affected by these variations in passivation and quantify these temperature-mediated effects, compared with those expected from standard diode equations. We confirm that devices with high V oc values at 25 °C show better high-temperature performance. However, we also argue that the precise device architecture, such as the presence of charge-transport barriers, may affect the temperature-dependent device performance as well.

Temperature compensation in potentiometry: isopotentials of pH glass electrodes and reference electrodes. Part II. Performance of commercial electrodes

Commercial glass electrodes were shown to have non-linear temperature characteristics with isopotential pH values up to 2 pH below the expected pHiso= 7.0. The use of calomel rather than silver-silver chloride reference electrodes causes a reduction of about 2 pH in the pHiso of an isothermal cell. Each unit by which pHiso is lower than the value assumed by the meter causes an error of –0.0035 pH K–1. The design of some reference electrodes makes it almost impossible for them to achieve rapid thermal equilibrium with the test solution and, hence, for proper temperature compensation to be applied. Cells containing such electrodes are not isothermal and may approach the character of cells with remote junction reference electrodes. Such cells may suffer from drifting e.m.f.s and give different temperature errors in solutions above and below the standardisation temperature. The liquid junction potential is shown to make a small contribution to the cell's temperature coefficient, so that the value of pHiso obtained for electrodes calibrated in standard buffers is 0.3 pH too high for use with dilute acid solutions.