Optical and Structural Analysis of Layer Thickness Effects on Transmission in Semitransparent Colorful Organic Photovoltaics

Organic photovoltaics (OPVs) offer significant potential for aesthetic, architectural, and indoor applications due to their unique features such as lightweight structure, low toxicity, mechanical flexibility, and customizable optical properties. A persistent challenge in the development of semitransparent OPVs lies in achieving vivid, tunable coloration without altering the photoactive layer composition, which often complicates fabrication and impacts device performance. To address this, the present study introduces a strategy for precise color control in OPVs by integrating a metal–dielectric–metal (Ag/SnO2/Ag) optical filter into an inverted device structure comprising ITO, ZnO, PM6:Y6, MoO3, and Ag. Through numerical simulations based on the Transfer Matrix Method (TMM), the influence of layer thicknesses on optical transmission and color modulation is systematically examined. The dielectric SnO2 layer is found to play a pivotal role in determining the resonance conditions for transmitted light, thereby enabling interference-based control over perceived color. By adjusting the SnO2 thickness from 60 nm to 130 nm, a broad spectrum of vivid colors ranging from deep blue to green, yellow, orange, red, and magenta can be realized. Additionally, an Ag layer thickness of 25 nm is identified as the optimum for balancing high optical transparency with sufficient electrical conductivity. This method provides a scalable and material-independent solution for achieving color versatility in OPVs, eliminating the need to modify the absorber layer. The findings demonstrate the effectiveness of optical cavity design in enhancing both the aesthetic and functional aspects of semitransparent OPVs. Such an approach opens new avenues for integrating colorful, energy-harvesting surfaces into applications like building-integrated photovoltaics (BIPV), smart windows, and decorative or wearable electronics. Overall, this work underscores the importance of optical engineering in enabling multifunctional solar technologies that align with emerging energy and design demands.