A method of fabricating monolithically-integrated optoelectronic modules comprising at least two series-interconnected optoelectronic components (104, 106), such as photovoltaic, diode, or light-emitting diode components, starting from an initial electrically insulating layer positioned either as a substrate under, or as a superstrate on top of, a stack of layers produced by the following steps conducted in the order (a), (b), (c) if said initial insulating layer is positioned for a substrate configuration, or in the order (c), (b), (a) if said initial insulating layer is positioned for a superstrate configuration, the method comprising producing said stack of layers by the steps of: (a) depositing an electrically conductive layer, called the back-contact layer, onto said insulating layer or onto the semiconductive layer (130, 140) from step (b); cutting at least one groove, herein called back-contact groove, into said back-contact layer so as to expose at least one continuous line of said insulating layer or of said semiconductive layer (130, 140), thereby providing at least one first and at least one second back-contact component (122, 124, 126, 128) that are electrically disconnected; (b) depositing at least one semiconductive layer (130, 140), including at least one semiconductive optoelectronically active layer, onto the layer (120. 150) deposited in the previous step (a) or (c), thereby filling said grooves (121, 151), and wherein said semiconductive optoelectronically active layer is a CIGS-type ABC 2 material, wherein A comprises copper, B comprises indium and gallium, and C comprises selenium; (c) depositing at least one conductive front-contact layer onto the semiconductive layer (130, 140) deposited in the previous step (b) or onto said insulating layer; cutting at least one groove therein, called front-contact groove, into said conductive front-contact layers, such as to expose at least one continuous line of said semiconductive layer (130,140) deposited in the previous step or said insulating layer, thereby providing at least one first and at least one second front-contact component (154, 156, 158) that are electrically disconnected, said first and second front-contact components (154, 156, 158) comprising parts that overlie corresponding first and second back contact components (122, 124, 126, 128); said method further comprising the step, for at least one of said second back-contact components (124, 126), of drilling at least one cell-to-cell via hole through layers deposited at steps (b) and (c) such that said cell-to-cell via hole exposes part of said back contact layer and/or said insulating layer, using a drilling process that generates heat such that heat of said drilling process causes a permanent change in the chemical composition of the surface of said cell-to-cell via hole within said semiconductive layer(s) (130, 140) by causing a permanently metallized copper-rich CIGS-type ABC 2 material surface (134, 136) so that the surface of said cell-to-cell via hole becomes electrically conductive, to establish an electrically conductive path between at least one of said first front-contact components (154, 156) and at least one corresponding second back-contact component (124, 126), thereby realizing at least two series-interconnected optoelectronic components (104, 106). (a) depositing an electrically conductive layer, called the back-contact layer, onto said insulating layer or onto the semiconductive layer (130, 140) from step (b); cutting at least one groove, herein called back-contact groove, into said back-contact layer so as to expose at least one continuous line of said insulating layer or of said semiconductive layer (130, 140), thereby providing at least one first and at least one second back-contact component (122, 124, 126, 128) that are electrically disconnected; (b) depositing at least one semiconductive layer (130, 140), including at least one semiconductive optoelectronically active layer, onto the layer (120. 150) deposited in the previous step (a) or (c), thereby filling said grooves (121, 151), and wherein said semiconductive optoelectronically active layer is a CIGS-type ABC 2 material, wherein A comprises copper, B comprises indium and gallium, and C comprises selenium; (c) depositing at least one conductive front-contact layer onto the semiconductive layer (130, 140) deposited in the previous step (b) or onto said insulating layer; cutting at least one groove therein, called front-contact groove, into said conductive front-contact layers, such as to expose at least one continuous line of said semiconductive layer (130,140) deposited in the previous step or said insulating layer, thereby providing at least one first and at least one second front-contact component (154, 156, 158) that are electrically disconnected, said first and second front-contact components (154, 156, 158) comprising parts that overlie corresponding first and second back contact components (122, 124, 126, 128);