Flexible substrates and devices including flexible substrates are provided. In an embodiment, a flexible substrate includes a first glass substrate material and a first organic light emitting device, disposed over the first flexible substrate, which includes a first emissive layer The first flexible substrate may have a thickness of not more than 300 μm, a flexural rigidity of 10−1 Nm to 10−6 Nm, a water vapor transmission rate of not more than 10−6 g per square meter per day, a refractive index of not more than 1.6, a glass transition temperature of at least 300 C, a Young's modulus of 60 to 90 GPa, and/or an optical transmission of at least 85% for light in the range of 400 to 800 nm.