In this paper we report a detailed study of emission dynamics of an organic solid-state laser structure so-called VECSOL standing for Vertical External-Cavity Surface-emitting Organic Laser recently developed in our group. An optical-optical efficiency of 43% and 6.3% was reported for a 4-mm-long cavity incorporating 18-μm-thick film of Poly(methyl methacrylate) (PMMA) doped with 1 wt.% of Rhodamine 640 when pumped with 7-ns-long and 0.5-ns-long pulses respectively. In order to understand the difference seen in lasing efficiency as a function of different parameters such as cavity length or pump pulse duration, Tang-Statz-deMars cavity rate equations are used to model the emission behavior in a pulsed regime. Based on this model, conversion efficiency could be optimized practically to values as high as 57%. Furthermore, some characteristics of this laser architecture such as lasing lifetime (up to 140 000 pulses at two times above lasing threshold), wavelength tuning (over 40 nm) and the system power scalability with potential operation up to mJ level are investigated.