Ideal p-n Diode Current Equation for Organic Heterojunction using a Buffer Layer: Derivation and Numerical Study

The equation of p-n diode current-voltage (J-V) of an organic heterojunction (HJ) including a hole and electron buffer layer is derived, and its characteristics are numerically simulated based on a polaron-pair model Giebink et al. (Forrest, Phys. Rev. B 82; 1-12, 2010). In particular, the correlation between a fraction of the potential drop for an electron/hole buffer (delta(e) (- b)/delta(h -) (b)) and for a donor (D)/acceptor (A) (delta(D)/delta(A)) is numerically investigated for J-V curves. As a result, the lowest diode current (DC) is obtained for the condition of delta(e -) (b)+ delta(A) congruent to 0 or delta(D) + delta(h -) (b) congruent to 1. It is suggested that it is important to characterize the lowest DC curve for the state of D/A blending with a condition of a fraction of the potential drop (delta(e) (- b)/delta(h -) (b)). Under these circumstances, the transport of holes (h(+)) from a DC source at the reverse bias is effectively limited.