PHOTOVOLTAIC DEVICE COMPRISING HEAT RESISTANT BUFFER LAYER, AND METHOD OF MAKING THE SAME
A photovoltaic device includes a substrate, a back contact layer disposed above the substrate, an absorber layer comprising an absorber material disposed above the back contact layer, and a buffer layer disposed above the absorber layer. The buffer layer includes a first layer comprising the absorber material doped with zinc, and a second layer comprising a zinc-containing compound and a cadmium-containing compound.
1 . A photovoltaic device comprising
a substrate;
a back contact layer disposed above the substrate;
an absorber layer comprising an absorber material disposed above the back contact layer; and
a buffer layer disposed above the absorber layer,
wherein the buffer layer includes a first layer comprising the absorber material doped with zinc, and a second layer comprising a zinc-containing compound and a cadmium-containing compound.
2 . The photovoltaic device of claim 1 , further comprising
a transparent conductive layer disposed over the buffer layer.
3 . The photovoltaic device of claim 1 , wherein the first layer of the buffer layer comprises copper indium gallium selenide (GIGS) doped with zinc in the range of from 0.1 atomic % to 5 atomic %.
4 . The photovoltaic device of claim 1 , wherein the first layer of the buffer layer has a thickness in the range of from 1 nm to 100 nm.
5 . The photovoltaic device of claim 1 , wherein the first layer of the buffer layer is further doped with cadmium.
6 . The photovoltaic device of claim 1 , wherein the second layer of the buffer layer has a two-layer structure, including a zinc-containing layer comprising the zinc-containing compound, and a cadmium-containing layer comprising the cadmium-containing compound.
7 . The photovoltaic device of claim 6 , wherein the zinc-containing layer has a thickness in the range of from 1 nm to 60 nm, and the cadmium-containing layer has a thickness in the range of 1 nm to 100 nm.
8 . The photovoltaic device of claim 1 , wherein the second layer of the buffer layer has a single-layer structure and comprises the zinc-containing compound disposed over the first layer of the buffer layer, and the cadmium-containing compound impregnating the zinc-containing compound.
9 . The photovoltaic device of claim 8 , wherein the zinc-containing compound in the second layer of the buffer layer is in a shape of selected from a group consisting of irregular particles, tubes, and spherical particles.
10 . A photovoltaic device comprising
a substrate;
a back contact layer disposed above the substrate;
an absorber layer comprising an absorber material disposed above the back contact layer; and
a buffer layer disposed above the absorber layer,
wherein the buffer layer includes a first layer comprising the absorber material doped with zinc, a second layer comprising a zinc-containing compound, and a third layer comprising a cadmium-containing compound.
11 . The photovoltaic device of claim 10 , wherein the first layer of the buffer layer comprises copper indium gallium selenide (GIGS) doped with zinc in the range of from 0.1 atomic % to 5 atomic %.
12 . The photovoltaic device of claim 10 , wherein the first layer of the buffer layer has the thickness in the range of from 5 nm to 20 nm.
13 . The photovoltaic device of claim 10 , wherein the second layer comprises at least one of zinc sulfide and zinc selenide, and has a thickness in the range of from 5 nm to 20 nm; and the third layer comprises cadmium sulfide and has a thickness in the range of from 5 nm to 60 nm.
14 . A method of fabricating a photovoltaic device, comprising
forming a back contact layer above a substrate;
forming an absorber layer comprising an absorber material above the back contact layer;
forming a first layer of a buffer layer, the first layer comprising the absorber material doped with zinc; and
forming a second layer of the buffer layer above the first layer, the second layer comprising a zinc-containing compound and a cadmium-containing compound.
15 . The method of claim 14 , wherein the first layer of the buffer layer is formed through doping zinc into a top surface of the absorber layer.
16 . The method of claim 14 , wherein the step of forming the second layer of the buffer layer comprises
forming a zinc-containing layer comprising a zinc-containing compound; and
forming a cadmium-containing layer comprising a cadmium-containing compound.
17 . The method of claim 16 , wherein the step of forming the second layer of the buffer layer comprises:
depositing a zinc-containing compound over the first layer of the buffer layer, and forming a cadmium-containing compound impregnating or disposed over the zinc-containing compound,
wherein the zinc-containing compound in the second layer of the buffer layer is in a shape of selected from a group consisting of irregular particles, tubes, and spherical particles.
18 . The method of claim 16 , wherein the zinc-containing layer and the cadmium-containing layer are two distinct layers.
19 . The method of claim 16 , where the steps of forming the zinc-containing layer and the cadmium-containing layer include using a chemical bath deposition (CBD) method.
20 . The method of claim 14 , further comprising forming a transparent conductive layer over the buffer layer.