A-SI:H ABSORBER LAYER FOR A-SI SINGLE- AND MULTIJUNCTION THIN FILM SILICON SOLAR CELLS
In order to improve a thin film solar cell with an amorphous silicon absorber layer being in single or in tandem configuration, the addressed absorber layer of a-Si:H is manufactured by plasma enhanced vapor deposition in an RF-SiH 4 plasma, wherein the deposition is performed at at least one of at the process pressure below 0.5 mbar and of at an RF power density below 370 W/14000 cm 2 .
1 ) A method of manufacturing an absorber layer of a-Si:H of a thin film solar cell by plasma-enhanced-vapor deposition PECVD in a RF-SiH 4 plasma, comprising at least one of the steps of
a) performing said deposition at a process pressure below 0.5 mbar
b) performing said deposition at a RF power density below 370 W/14 000 cm 2 .
2 ) The method of claim 1 comprising steps a) and b).
3 ) The method of one of claim 1 or 2 comprising selecting said process pressure value to be at least 0.3 mbar.
4 ) The method of claim 1 comprising performing only step a) at a pressure value of 0.45 mbar.
5 ) The method of claim 1 comprising performing only step b) at a power density value of 270 W/14000 cm 2 .
6 ) The method of claim 2 thereby selecting said process pressure to 0.4 mbar and said power density to 230 W/14000 cm 2 .
7 ) A photovoltaic absorber layer of a-Si:H comprising at least one of:
i. an microstructure factor R (%) less than 10.5
ii. a H content c H (at. %) below 13.7.
8 ) The absorber layer of claim 7 manufactured according to the method of one of claims 1 to 6 .
9 ) The absorber layer of claim 7 or 8 manufactured according to one of claims 2 , 3 , 6 .
10 ) A single junction a-Si solar cell, comprising a low-pressure-chemical-vapor deposited (LPCVD) ZnO front contact layer comprising an absorber layer according to one of claims 7 to 9 .
11 ) The a-Si solar cell according to claim 10 wherein the absorber layer has a thickness of 265 nm.
12 ) The a-Si solar cell of one of claim 10 or 11 wherein there is valid, at least one of:
I. The current density J sc is higher than 16.8 ma/cm 2
II. The efficiency is higher than 10.62%.
13 ) The a-Si solar cell of claim 12 wherein I. and II. are valid.
14 ) The a-Si solar cell of one of claims 10 to 12 having an absolute stabilized efficiency after 1000 h light soaking of at least 8.25% and a relative light induced degradation of less than 22%.
15 ) A micromorph solar tandem cell comprising a top and a bottom cell, wherein the top cell comprises an a-Si absorber layer according to claim 7 wherein i. and ii. are fulfilled, preferably manufactured according to claim 9 .