Carmalt was made a Royal Society Dorothy Hodgkin Research Fellow at University College London in 1997. She has held many positions at UCL, including lecturer, professor, vice dean and eventually Head of Department. When she was made Head of Department in 2016 she was the first woman to hold the position.
Carnalt specialises in the synthesis of highly volatile, non-toxic molecular precursors for the growth of thin films of transparent conducting oxides (TCOs). TCOs are used in a range of different technologies, including computers, mobile phones and photovoltaic devices. The materials most commonly used to make TCOs (indium and tin) are available in limited quantities, expensive and complicated to process. Carmalt is interested in thin film deposition techniques, including chemical vapour deposition, aerosol-assisted chemical vapour deposition (AACVD) and atomic layer deposition. In particular, AACVD offers the potential for large-area TCO coatings based on nanoparticle dispersions.