Quantum efficiency of a-Si:H p-i-n solar cells in the 250 to 375 K range-insights from defect pool modelling

A variation of the temperature T of a p-i-n solar cell shifts the Fermi level and thereby changes the occupation of the defect densities within the device according to the defect model used. Thus the T dependence of the quantum efficiency (QE) promises to give a clearer insight into the defect distribution and recombination within the device. With decreasing T both the red and the blue response of an a-Si:H p-i-n solar cell decrease, the loss in the red being due to the i layer gap shift. The drop on the short wavelength side with decreasing T is attributed to a change of charge state of the D⁺ in the nonequilibrium case within the first 100 nm of the i-layer. This negative space charge diminishes the field spike near the p/i interface and reduces the hole concentration there by recombination