The purpose of this work is to analyze the spectrum of an asymmetric triangular double quantum well (TDQW) subject to an external electric field. We show that, for a particular value of this field, the correlation between two wells is strongest. In this special regime, this system behaves like a heteronuclear unpolarized diatomic molecule. To understand these features, we discuss the behavior of the spectrum as the value of the electric field as well as the width of the well vary. In this way, theoretical results of the ground and the first levels of TDQW are compared with single triangular quantum well ones. Based on this simple analysis, we show that it is possible to understand the mechanism of formation of the TDQW spectra. In addition, due to these peculiar spectrum features, our results suggest that possible lasing action based on TDQW system can exhibit 'red' as well as 'blue' shift in the fundamental spectrum emission. (C) 2002 Elsevier Science Ltd. All rights reserved.