Leakage currents, electronic devices

Mobile ions, such as sodium or potassium, tend to migrate to thep-n junction of the IC device where they acquire an electron, and deposit as the corresponding metal on the p-n junction this consequendy destroys the device. Furthermore, mobile ions also support leakage currents between biased device features, which degrade device performance and ultimately destroy the devices by electrochemical processes such as metal conductor dissolution. 

In a bulk-heterojunction photovoltaic cell with methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) as an electron acceptor, alternating copolymer 19 (Fig. 9), derived from 2,7-fluorene and 2,5-dithienylsilole, can show impressive performance as the electron donor.31 In a device configuration of ITO/PEDOT/active layer/Ba/Al, the dark current density—bias curve shows a small leakage current, suggesting a continuous, pinhole-free active layer in the device. Under illumination of an AM 1.5 solar simulator at 100 mW/cm2, a high short-circuit current of 5.4 mA/cm2, an open-circuit voltage of 0.7 V, and a fill factor of 31.5% are achieved. The calculated energy conversion efficiency is 2.01%. 

Solution The circuit corresponds to the dielectric response of a semiconductor device. The term Csc represents the space-charge capacitance, and the terms Rt,i, Ct,i, Rt,i, and account for the potential-dependent occupancy cfdeep-leoel electronic states, which typically have a small concentration. The term Ri accounts for the leakage current, which would be equal to zero for an ideal dielectric. 

The autodischarge of the device is related to the electrical properties of the electrolyte. Solid electrolytes exhibit only one type of ionic carrier and have a very low electronic conductivity. They thus give a lower leakage current and have a larger voltage safeguard than liquid electrolytes in which other charge carriers are also present. 

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