Figures index : Hello Future! Printed Electronics as a Hands-On Experiment for Science Teaching : Science and Education Publishing

Figures index

World Journal of Chemical Education. 2021, 9(4), 104-110 doi:10.12691/wjce-9-4-2

Figure 2. Placing the substrate and sieve into the printing-machine (left) and optical detection of the markers for calibration (right)

Figure 3. Screen-printer with rubber blade during printing process (left) and professional UV-chamber for curing (right)

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

Figure 6. Structure-model derived from the flipped device. The insulating varnish is neglected in the structure-model for simplification. The Cu₂S-crystallites (brown ellipses) have a narrow band-gap (see band-model in the upper right corner) and play a vital role for the bipolar injection mechanism

Figure 7. a) Charge carriers are released from Cu₂S-crystallites into the semiconductor layer due to the high electric field. b) Charge carriers move towards the electrodes and get captured in the traps of the semiconductor. c) Phase change of alternating current inverts the direction of the bipolar injection. The injected charge carriers encounter trapped ones with opposite charge. d) Trapped electrons and holes recombine under light emission