Printed Bypass Diodes: Unlocking Reliable Next‐Generation Printed Photovoltaic Modules

Shading remains a major obstacle for photovoltaic (PV) technologies, particularly as flexible and printed devices move beyond silicon, where conventional bypass diodes cannot be directly integrated. Here, we report the first demonstration of fully printed bypass diodes specifically designed to protect next‐generation printed PV modules. The devices are fabricated using a simple wet‐deposition process based on an abundant, water‐soluble, and nontoxic tin dioxide (SnO 2 ) colloidal ink modified with polyvinyl alcohol to enhance process reliability and film uniformity. The diode structure comprises a SnO 2 nanoparticle layer (3–5 nm, cassiterite phase) sandwiched between indium tin oxide (ITO) and silver electrodes, forming an ohmic and a Schottky contact, respectively. Quantum confinement in SnO 2 nanoparticles leads to a blueshifted optical absorption with a bandgap of 4.20 eV and an effective reduced mass of 0.08 m e . The optimized devices exhibit excellent rectifying behavior, with an ON/OFF ratio exceeding six orders of magnitude and a reverse current as low as 4 × 10 −4 mA cm −2 , ensuring negligible power dissipation in the bypass diode under illumination. These printed diodes represent a key step toward the industrial realization of reliable, large‐area, fully printed PV modules.