Based on the developed analytical absorption model for 0.53 eV GaInAsSb alloy and the suggested material parameters, evaluating active layer controlled thermal conversion has been systematically done for both p-on-n and n-on-p configuration in its normal and inverted construction. A universal, spectrum-insensitive optimal doping, N-a(d) = 3 x 10(17) cm(-3), is observed in diode light-doped layer for all concerned configurations. By improving the doping in the light-doped layer, thickness compensation between emitter and base has been observed for normal structures and, for each considered structure, suboptimal structures can be employed by consuming less material to achieve comparable output as that for optimal one. Comparing to GaSb diode, 2-3 fold efficiency enhancement can be expected for low-temperature spectrum illumination, making the concerned device an efficient candidate for low-temperature TPV applications. (C) 2014 Elsevier Ltd. All rights reserved.