Figure 5. a) Band model of ZnS. In the ground state electrons are located in the valance-band (VB), whereas the conduction-band (CB) is empty.b) Band model of copper doped zinc sulfide (ZnS:Cu) with activator-level (AL) and coactivator-level (CL). In the ground-state electrons are located in the VB and AL, whereas the CB and CL are empty. c) During electroluminescence electrons are injected into the CB and get trapped in the CL. Simultaneously, the electrons from the VB are extracted, leaving a hole (i.e. a positive charge) behind. These holes get trapped in the AL.d) When trapped electrons on the CL encounter trapped holes on the AL, the charge carriers recombine under emission of visible light

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Hello Future! Printed Electronics as a Hands-On Experiment for Science Teaching

Lena Halbrügge, Amitabh Banerji, Sven Rösler

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