In the last few decades, electroluminescence in organic semiconductors has been developed and commercialised into a flourishing industry. Compared with traditional inorganic semiconductors, OLED has good scalability, simple device structures, thin and lightweight flexible, high resolution (< 5 µm pixel size), fast switching time (1-10 µs), broad colour gamut and good contrast [1,2]. However, efficient deep blue OLEDs remain one of the key challenges limiting the broader applications of OLED technology, such as display screens and white lighting. The lifetime of blue OLEDs is short and the efficiency is low compared to the other two RGB colours, green and red. The recent discovery of carbene-metal-amide (CMA) type emissive complexes has opened up a new route to achieving efficient blue emissione [3]. Initial reports have centred around variants of the archetype CMA1, which exhibits high luminescence efficiency, good chemical stability, fast intersystem crossing and short radiative triplet lifetimes (within 350 ns). CMA1 is however a mid-green emitter.  Previous work by Conaghan et al. showed that OLED devices based on CMA1 achieve high external quantum efficiency up to 26.9% in host-guest emissive layers and the EL spectra are dependent on both CMA1 doping concentration and the host molecule [4]. Emission colour can be tuned from mid-green to sky blue without replacing dopant. Here I will show from a photophysics perspective how the emission of CMA1 may be tuned by utilising intermolecular interactions with a variety of host materials to both restrict spectral diffusion and shift the relative energy of its excited states. The result is that the emission of CMA1 can be tuned into the blue range without altering the chemical structure of emitter. We determine that dipole-dipole interactions are one of the most important parameters for these composites, with polar hosts such as TSPO1 (Diphenyl-4-triphenylsilylphenyl-phosphine oxide) host with a large static dipole moment (around 4.1 D) achieving the largest shifts. Similar shifts can also be observed in other hosts with different nature, for example PVK (Poly(9-vinylcarbazole)), TCP (1,3,5-Tris(N-carbazolyl)benzene), mCP (1,3-Bis(N-carbazolyl)benzene) and I will discuss the spectroscopic and photophysics evidence for the different parameters and mechanisms involved. Since this strategy does not rely on a particular emitter, the same approach can be extended to other materials in the CMA class to shift their emission. This method opens up a new way of tuning the emission colour of OLED without actually changing the chemical nature of emitter, and thus does not compromise attractive properties. This also reveals the impact of intermolecular interactions on emitter and the mechanism of rotation dependent electronic structures.