Improving the stability of amorphous silicon solar cells by chemical annealing

Abstract

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Environmental Effects on the Operation of Triple-Junction Flexible Photovoltaic Panels

“…For the case of amorphous silicon thin films, annealing using hydrogen or helium plasma produced cells with better fill factors and suffered less degradation due to the Staebler-Wronski effect [12].…”

“…0 ref : reference saturation current in Amperes [A] T C ref : reference temperature of cells in Kelvin [K] E g : band gap energy in electron volts [eV ] k B : Boltzmann's constant in Joules per Kelvin [JK −1 ]The final part of the one-diode model is the current through the shunt resistance, I sh . This resistance models the non-ideality property of solar cells that allows separated electron-hole pairs to recombine through crystal boundaries[12]…”

Fabrication of high quality, low bandgap amorphous Silicon & amorphous Silicon Germanium alloy solar cell by Chemical Annealing

“…Hydrogenated amorphous silicon (a-Si:H) is used for a several applications such as thin film transistor [1] [9], LCD [3], photosensors [10], photoreceptors [11] [12]. The advantages of A-Si is that it is cheaper to fabricate as compared to crystalline Silicon solar cells and also it has high absorption coefficient over visible region of solar spectrum as it acts like a direct bandgap material because the law of conservation of momentum is relaxed [13]. A-SiGe similarly provides us with the alternative of fabrication low bandgap solar cells, but it is affected by the presence of greater defect density.…”

“…These extra states change the Tauc's bandgap , depending on the hydrogen content-from about 1.5eV for pure A-Si to almost 2.0eV when 30 at. % H content is recorded [13]. Very close to the tail states exists several deep-level bands in the forbidden gap, believed to be related to dangling bonds [2].…”

“…This has been made use of in our research as discussed in result section. Some prominent properties of device-quality a-Si:H are given [13] below:-(i) Bandgap: 1.62 to 1.8 eV (ii) Urbach energy: 42 to 45 meV (iii) Photoconductivity: 10 -4 S/cm to 10 -5 S/cm (iv) Dark conductivity: 10 -10 S/cm to 10 -11 S/cm (v) μτ(mobility-lifetime product) for hole:…”