We　demonstrate　a　novel　structure　for　a　quantum-dot　light-emitting　diode　(QD-LED)　with　wide-range　colour-tuneable　pixels,　fabricated　via　full　solution　processing.　The　proposed　device　has　a　symmetrical　structure　produced　via　stacking　of　an　inverted-structure　diode　with　a　green　QD　emission　layer　(EML)　and　normal-structure　diode　with　a　red　QD　EML.　It　is　an　electron-only　device;　however,　a　charge　generation　layer　in　the　middle　of　the　device　generates　holes　for　the　formation　of　excitons.　Depending　on　the　polarity　of　the　applied　voltage,　either　the　bottom　inverted　unit　or　the　top　normal　unit　is　operated,　thereby　emitting　green　or　red　light,　respectively.　The　working　mechanism　of　the　device　is　investigated　via　analysis　of　the　charge　generation　mechanism　and　carrier　transport　path.　In　addition,　the　colour　tunability　is　verified　using　a　simple　alternating　current　(AC)　driving　scheme;　the　duty　cycle　modulation　of　the　AC　signal　enables　fine　colour　adjustment　over　a　broad　range,　from　pure　green　to　pure　red.　Thus,　our　colour-tuneable　QD-LED　with　vertically　stacked　independently　operated　sub-pixels　can　open　a　promising　pathway　towards　cost-effective　ultra-high-resolution　displays.　©　2020　The　Royal　Society　of　Chemistry.