In this study, the application of chalcogenide-based inorganic hole transport layers, specifically copper indium gallium selenide (CuInxGa_1-xS₂) nanocrystals, in conjunction with carbon or gold back electrodes is explored. The carbon electrodes consist of a mixture of graphite, carbon nanotubes (CNTs), carbon black nanoparticles, and hydrophobic polymers such as polystyrene or polymethyl methacrylate, all dissolved in a solvent compatible with the perovskite layer. This innovative approach not only reduces production costs but also enhances mechanical stability and flexibility, making it suitable for large-scale applications. Optimizing the composition of the carbon electrode is crucial; our results indicate that varying the weight ratio of carbon black to graphite significantly impacts both sheet resistance and resistivity, ultimately affecting overall device performance. The integration of CuInxGa1-xS2 improves environmental stability due to its inherent robustness. It is systematically investigated how changes in synthesis parameters—such as temperature, capping agent, and variations in the indium-to-gallium ratio—affect band alignment, hole transport resistance, and photovoltaic properties in triple-cation perovskite solar cells (PSCs). Techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and incident photon-to-current efficiency (IPCE) measurements are employed. Results reveal that increasing the indium content in CuInxGa1-xS2 reduces charge transfer resistance at the interface between the hole collector and the perovskite layer, which correlates with an increase in fill factor. The highest efficiency achieved is 16.45% for triple-cation PSCs utilizing CuIn0.75Ga0.25S2/carbon hole collectors. Transmission electron microscopy (TEM) images show that increasing the growth temperature from 220 °C to 275 °C significantly enlarges the size of CuIn0.75Ga0.25S2 nanocrystals and improves their crystallinity, as confirmed by XRD patterns. This enhancement leads to an increase in open-circuit voltage (V_oc) from 0.941 V to 1.092 V and an average fill factor improvement from 60% to 73%. By creating a nanocomposite of CIGS nanocrystals with a small amount of Spiro-OMeTAD, an efficiency of 18.72% is acheaved, comparable to reference PSCs utilizing highly doped Spiro-OMeTAD, which exhibit an efficiency of 18.5%. Additionally, polyvinyl carbazole serves as an interfacial modifier to deactivate surface defects by utilizing bonding electron pairs on nitrogen atoms and uncoordinated lead atoms on the perovskite surface. This modification helps suppress charge carrier recombination. These interfacial layers also act as barriers against the penetration of carbon black and CuInS₂ nanoparticles into the perovskite layer while functioning as a binder to enhance the interfacial area. By substituting conventional heating methods for electron transport layer sintering with rapid light-curing techniques using halogen or mercury lamps, significant reductions in energy consumption and processing time is achieved without compromising efficiency. Given that both the carbon back electrode and the entire PSC structure warm under standard AM1.5 light intensity, this design is particularly well-suited for indoor applications where overheating is less likely. For HTL-free PSCs with carbon electrodes, notable differences between current densities calculated from external quantum efficiency under low light intensity versus those measured under standard AM1.5 conditions are observed. However, for PSCs with modified CIGS/carbon hole collectors, this difference is minimized. For indoor applications, addressing defects at the interfaces among CIGS nanocrystals, between the carbon electrode and perovskite layer, and reducing energy level differences across various structural layers become critical factors for optimizing performance. Utilizing low-temperature inorganic hole transport materials along with carbon electrodes helps prevent the evaporation of halides and organic cations, thereby reducing defect formation—an essential consideration for indoor applications.