Reduction of Hole Injection Barrier Height at TCO/P Interface Using a-SiO:H Interlayer

In a thin film, p-i-n solar cell the front contact interface loss due to high band bending between TCO front contact and p-type window layer can be minimized by inserting a wind band gap hydrogenated amorphous silicon oxide interlayer at the TCO/p interface. In this paper, a simulation and experimental investigation on the performance of p-i-n solar cell by inserting the intrinsic hydrogenated amorphous silicon oxide (i-a-SiO:H) at the TCO/p interface has been carried out. A device quality wide bandgap i-a-SiO:H interlayer was prepared at 230 °C substrate temperature by using radio frequency plasma-enhanced chemical vapor deposition (13.56 MHz RF-PECVD) technique. The experimental results in this study showed that the integration of interlayer at the TCO/p interface reduces the barrier height from 0.513 to 0.472 eV resulting the power conversion efficiency (η) of 9.38% and fill factor (FF) of 74.8% for a single-junction p-i-n solar cell with an active area of 1.0 cm
²
. In addition, the electrically and optically calibrated simulations also confirm that the application of interlayer at the TCO/p interface reduces the barrier height. As a result, the electric filed over the frontal region has decreased, which aided to minimize the recombination of photogenerated holes with back diffusing electrons at the front contact. The spectral response of the solar cell with interlayer has also improved significantly in the lower wavelength region (350-600 nm) in comparison to the cell without an interlayer at the TCO/p interface.