The electrical properties of chloroindium phthalocyanine (ClInPc) in a Au-ClInPc-metal sandwich structure were measured, both in a vacuum (< 1.3 mPa) and at atmospheric pressure using Au, Sn and Al top contacts. In addition to current-voltage characteristics, the electroluminescence (EL) from the devices was measured and, in a vacuum, the electron emission (EE). At atmosphere all the devices show a nonlinear conduction that decays slowly over many hours. In the vacuum the Au-ClInPc-Au devices display a voltage-controlled negative differential resistance (NDR) accompanied by a peak in the electroluminescence and high field electron emission. The Au-ClInPc-Sn devices in the vacuum show an NDR with a distinct valley but with no detectable electroluminescence or electron emission. The Au-ClInPc-Al devices do not display NDR under vacuum, but show nonlinear conduction approximately 30 times greater than that observed at atmosphere.