The advent of graphene and other 2D materials has led to the development of van der Waals heterostructures, which have shown versatility in creating various electronic devices. This paper introduces a new approach to these heterostructures by engineering quantum wells (QWs) with atomic precision. The authors demonstrate light-emitting diodes (LEDs) by stacking metallic graphene, insulating hexagonal boron nitride (hBN), and semiconducting monolayers in complex sequences. These devices exhibit extrinsic quantum efficiency of nearly 10% and can be tuned over a wide range of frequencies by selecting different 2D semiconductors. The heterostructures are prepared on elastic and transparent substrates, making them suitable for flexible and semi-transparent electronics. The performance of the LEDs is enhanced by using multiple QWs, achieving quantum efficiencies up to 8.4%. The technology is scalable and compatible with the growing demand for flexible and transparent electronics.The advent of graphene and other 2D materials has led to the development of van der Waals heterostructures, which have shown versatility in creating various electronic devices. This paper introduces a new approach to these heterostructures by engineering quantum wells (QWs) with atomic precision. The authors demonstrate light-emitting diodes (LEDs) by stacking metallic graphene, insulating hexagonal boron nitride (hBN), and semiconducting monolayers in complex sequences. These devices exhibit extrinsic quantum efficiency of nearly 10% and can be tuned over a wide range of frequencies by selecting different 2D semiconductors. The heterostructures are prepared on elastic and transparent substrates, making them suitable for flexible and semi-transparent electronics. The performance of the LEDs is enhanced by using multiple QWs, achieving quantum efficiencies up to 8.4%. The technology is scalable and compatible with the growing demand for flexible and transparent electronics.