PHOTOVOLTAIC DEVICES AND METHODS OF MAKING
Photovoltaic devices ( 100 ) with type ll-VI semiconductor absorber materials ( 160 ) having p-type contact layers ( 180 ) are obtained by forming a ll-VI absorber layer over a substrate stack ( 113 ), wherein the type II material includes cadmium (Cd) and the type VI material includes tellurium (Te); contacting an alkaline wash fluid, comprising a hydroxide, to a second surface of the absorber layer to produce a Cd-rich surface, depositing a p-type contact layer ( 180 ) over the absorber layer ( 160 ), whereby the p-type contact layer is directly adjacent to the Cd-rich layer, and wherein the p-type contact layer comprises at least one of: PTAA, P3HT, poly-TPD, TFB, TTF-1, TF8-TAA, TIF8-TAA, SGT-407, PCDTBT, SpiroOMeTAD, anthracene-based HTM, polythiophene, semiconducting polymers, NiO, CuSCN, or Cui; and depositing a conductive layer ( 190 ) over the p-type contact layer.
1 . A method of making a photovoltaic device comprising:
forming an absorber layer over a substrate stack, wherein the absorber layer comprises a type II-VI semiconductor material, wherein the type II material includes cadmium (Cd) and the type VI material includes tellurium (Te);
contacting an alkaline wash fluid, comprising a hydroxide, to a second surface of the absorber layer to produce a Cd-rich surface, wherein a ratio of Cd to Te is greater than 1:1;
depositing a p-type contact layer over the absorber layer,
whereby the p-type contact layer is directly adjacent to the Cd-rich surface, and
wherein the p-type contact layer comprises at least one of: PTAA, P3HT, poly-TPD, TFB, TTF-1, TF8-TAA, TIF8-TAA, SGT-407, PCDTBT, SpiroOMeTAD, anthracene-based HTM, polythiophene, semiconducting polymers, NiO, CuSCN, or CuI; and
depositing a conductive layer over the p-type contact layer.
2 . The method of claim 1 , wherein the step of depositing the p-type contact layer is performed at a substrate temperature at or below 150° C.
3 . The method of claim 1 , wherein the hydroxide comprises at least one of: sodium hydroxide (NaOH), potassium hydroxide (KOH), or tetramethylammonium hydroxide ((CH 3 ) 4 N(OH)) TMAH.
4 . The method of claim 1 , wherein the p-type contact layer comprises PIF8-TAA, poly-TPD, or PTAA undoped or doped with F4-TCNQ.
5 . The method of claim 1 , wherein the absorber layer is doped with at least one dopant selected from phosphorus, arsenic, antimony, or bismuth.
6 . The method of claim 1 , wherein the Cd-rich surface has a ratio of Cd to Te greater than 1:1 and equal to or less than 4:1.
7 . The method of claim 1 , wherein the p-type contact layer is deposited by slot-die coating, blade coating, roll coating, spray coating, spin coating, evaporation, or sol-gel formation.
8 . A photovoltaic device comprising:
an absorber layer on a substrate stack, the absorber layer comprising a type II-VI semiconductor, wherein the type II material includes cadmium (Cd) and the type VI material includes tellurium (Te);
a p-type contact layer on the absorber layer, the p-type contact layer comprising at least one of PTAA, P3HT, poly-TPD, TFB, TTF-1, PF8-TAA, PIF8-TAA, SGT-407, PCDTBT, SpiroOMeTAD, anthracene-based HTM, polythiophene, semiconducting polymers, NiO, CuSCN, or CuI; and
a conductive layer on the p-type contact layer;
wherein the p-type contact layer is directly adjacent to a second surface of the absorber layer at a passivated interface, and the second surface of the absorber layer is a Cd-rich surface, wherein a ratio of Cd to Te is greater than 1:1.
9 . The photovoltaic device of claim 8 , wherein the p-type contact layer has a thickness in a range between 0.5 nm and 100 nm.
10 . The photovoltaic device of claim 8 , wherein the absorber layer is doped with at least one dopant selected from phosphorus, arsenic, antimony, or bismuth; and wherein the p-type contact layer comprises PIF8-TAA, PF8-TAA, poly-TPD, TFB, or PTAA.
11 . (canceled)
12 . The photovoltaic device of claim 8 , wherein the p-type contact layer comprises PTAA.
13 . The photovoltaic device of claim 8 , wherein:
the absorber layer comprises cadmium telluride selenide;
the absorber layer is doped with at least one dopant selected from arsenic, antimony, or bismuth; and
the p-type contact layer comprises PTAA, P3HT, TTF-1, SGT-407, SpiroOMeTAD, or NiOx.
14 . The photovoltaic device of claim 8 , wherein the absorber layer comprises cadmium telluride selenide.
15 . (canceled)
16 . The photovoltaic device of claim 8 , wherein:
the conductive layer is adjacent to the p-type contact layer, and
the conductive layer comprises at least one metal or metal nitride.
17 - 20 . (canceled)
21 . The method of claim 1 , wherein the p-type contact layer is heated at a temperature in a range of 80-150° C. prior to the step of depositing a conductive layer.
22 . The method of claim 21 , wherein heat treatment of the p-type contact layer is performed using a hot plate, an oven, and or a pressure-controlled heating chamber.
23 - 27 . (canceled)
28 . The method of claim 1 , wherein the absorber layer comprises cadmium telluride selenide.
29 . The method of claim 1 , wherein the p-type contact layer has a thickness in a range between 0.5 nm and 100 nm.
30 . The method of claim 1 , wherein the conductive layer is adjacent to the p-type contact layer, and the conductive layer comprises at least one metal or metal nitride.
31 - 43 . (canceled)
44 . The p-type contact layer of claim 8 , wherein the type II-VI semiconductor comprises cadmium, tellurium, selenium, and zinc, and wherein the type II-VI semiconductor is doped with arsenic.