THIN-FILM PHOTOVOLTAIC DEVICES WITH DISCONTINUOUS PASSIVATION LAYERS
In various embodiments, photovoltaic devices incorporate discontinuous passivation layers (i) disposed between a thin-film absorber layer and a partner layer, (ii) disposed between the partner layer and a front contact layer, and/or (iii) disposed between a back contact layer and the thin-film absorber layer.
1 . A photovoltaic device comprising:
a back contact layer comprising a conductive material;
a thin-film absorber layer disposed over and in electrical contact with the back contact layer and having a doping polarity;
a partner layer disposed over and in electrical contact with the thin-film absorber layer, the partner layer having a doping polarity opposite that of the thin-film absorber layer, the partner layer and thin-film absorber layer thereby forming a p-n junction;
a front contact layer disposed over and in electrical contact with the partner layer; and
at least one of:
a first discontinuous passivation layer disposed between the thin-film absorber layer and the partner layer, the partner layer making electrical contact with the thin-film absorber layer only through discontinuities in the first discontinuous passivation layer;
a second discontinuous passivation layer disposed between the partner layer and the front contact layer, the front contact layer making electrical contact with the partner layer only through discontinuities in the second discontinuous passivation layer; or
a third discontinuous passivation layer disposed between the back contact layer and the thin-film absorber layer, the thin-film absorber layer making electrical contact with the back contact layer only through discontinuities in the third discontinuous passivation layer.
2 . The photovoltaic device of claim 1 , wherein the front contact layer comprises a transparent conductive oxide.
3 . The photovoltaic device of claim 1 , wherein the back contact layer comprises molybdenum.
4 . The photovoltaic device of claim 1 , wherein the back contact layer comprises a sodium-containing conductive material.
5 . The photovoltaic device of claim 4 , wherein the sodium-containing conductive material comprises at least one of Mo:NaF or Mo:Na 2 MoO 4 .
6 . The photovoltaic device of claim 1 , wherein the absorber layer comprises amorphous silicon.
7 . The photovoltaic device of claim 1 , wherein the absorber layer comprises CdTe.
8 . The photovoltaic device of claim 1 , wherein the absorber layer comprises chalcopyrite (Cu(In,Ga)(S,Se) 2 ).
9 . The photovoltaic device of claim 1 , wherein the absorber layer comprises kesterite (Cu 2 (Zn,Fe)Sn(S,Se) 4 ).
10 . The photovoltaic device of claim 1 , wherein at least one of the first, second, or third discontinuous passivation layers comprises an insulator having a dielectric constant greater than or approximately equal to 3.9.
11 . The photovoltaic device of claim 1 , wherein at least one of the first, second, or third discontinuous passivation layers comprises an insulator having a dielectric constant greater than or approximately equal to 10.
12 . The photovoltaic device of claim 1 , wherein at least one of the first, second, or third discontinuous passivation layers has a band gap exceeding 3 eV.
13 . The photovoltaic device of claim 1 , wherein at least one of the first, second, or third discontinuous passivation layers has a band offset to an adjoining layer exceeding 1 eV.
14 . The photovoltaic device of claim 13 , wherein the band offset is a type-I band offset.
15 . The photovoltaic device of claim 1 , wherein at least one of the first, second, or third discontinuous passivation layers comprises CaO, MgO, or ZnS.
16 . The photovoltaic device of claim 1 , further comprising a sodium-containing layer disposed between the back contact layer and the thin-film absorber layer.
17 . The photovoltaic device of claim 16 , wherein the sodium-containing layer comprises at least one of NaF or Na 2 Se.
18 . The photovoltaic device of claim 1 , further comprising a discontinuous reflector layer disposed between the back contact layer and the thin-film absorber layer, the discontinuous reflector layer reflecting solar energy passing through the absorber layer back toward the absorber layer.
19 . The photovoltaic device of claim 18 , wherein the discontinuous reflector layer comprises at least one of aluminum, silver, titanium dioxide, or zirconium nitride.
20 . The photovoltaic device of claim 1 , wherein the photovoltaic device comprises the first discontinuous passivation layer.
21 . The photovoltaic device of claim 1 , wherein the photovoltaic device comprises the second discontinuous passivation layer.
22 . The photovoltaic device of claim 1 , wherein the photovoltaic device comprises the third discontinuous passivation layer.
23 . The photovoltaic device of claim 1 , wherein the photovoltaic device comprises the first discontinuous passivation layer, the second discontinuous passivation layer, and the third discontinuous passivation layer.
24 . The photovoltaic device of claim 1 , wherein the photovoltaic device comprises the first discontinuous passivation layer and the third discontinuous passivation layer.
25 . The photovoltaic device of claim 1 , wherein the photovoltaic device comprises the first discontinuous passivation layer and the second discontinuous passivation layer.
26 . The photovoltaic device of claim 1 , wherein the photovoltaic device comprises the second discontinuous passivation layer and the third discontinuous passivation layer.