In fact, a 1500 nm GaAs Solar Cell with photonic crystals achieves the same short circuit current as an unpatterned 4000 nm thick cell. These findings are significant because they afford a sizeable reduction in active layer thickness, and therefore a reduction in expensive epitaxial growth time and cost, yet without compromising performance.
Conventional photovoltaic devices are currently made up of relatively thick semiconductor layers, ~150 µm for silicon and 2–4 µm for Cu(In,Ga)(S,Se)2, CdTe or III–V direct bandgap semiconductors. Ultrathin solar cells using 10 times thinner absorbers could lead on to considerable savings in material and time interval . Theoretical models suggest that light trapping can catch up on the reduced single-pass absorption, but optical and electrical losses have greatly limited the performances of previous attempts. Here, we propose a technique supported multi-resonant absorption in planar active layers, and that we report a 205-nm-thick GaAs photovoltaic cell with a licensed efficiency of 19.9%. It uses a nanostructured silver back mirror fabricated by soft nanoimprint lithography. Broadband light trapping is achieved with multiple overlapping resonances induced by the grating and identified as Fabry–Perot and guided-mode resonances. A comprehensive optical and electrical analysis of the entire photovoltaic cell architecture provides a pathway for further improvements and shows that 25% efficiency may be a realistic short-term target.
Abstract:p-layer thickness dependence ideality factor, series resistance and barrier height had been investigated of a contact GaAs diode. photovoltaic cell response under sun light illumination was taken and it had been found that efficiency, fill factor and short current increased with the thickness of p-GaAs but after a particular thickness all this parameters decreased with increase in thickness. The efficiency of the cell was reached maximum 12.7% at atmosphere 1 for a 3 μm p layer thickness.