A charge carrier separation device for adiabatic cooling of hot charge carriers, the device comprising a first n-type semiconductor doped region and a second p-type semiconductor doped region, wherein the regions (2, 3) are separated by a junction (1, 7) susceptible upon heating or illumination to creation of positively charged and negatively charged mobile charge carriers, wherein the first n-type semiconductor doped region is further connected to a negative electric contact for collecting the negatively charged mobile charge carriers and the second p-type semiconductor doped region is further connected to a positive electric contact for collecting the positively charged mobile charge carriers, each region (2, 3) thus having a junction end and a contact end and the junction (1, 7) thus having an n-side and a p-side, characterised in that the first n-type semiconductor doped region comprises a non-uniform doping profile in which the donor dopant density N D ( x n) at a distance x n measured from the junction end of the first n-type semiconductor doped region towards the negative electric contact varies according to the equation N D x n = N D 0 T n x n T h 3 2, where N D is a donor doping density at the junction end of the first n-type semiconductor doped region where x n = 0; T n (x n) is a charge carrier temperature at a distance x n measured from the junction end of the first n-type semiconductor doped region towards the negative electric contact; and T h is a charge carrier temperature at the junction end of the first n-type semiconductor doped region where x n = 0, T h being higher than T n, and/or in that the second p-type semiconductor doped region comprises a non-uniform doping profile in which the acceptor dopant density N A ( x p) at a distance x p measured from the junction end of the second p-type semiconductor doped region towards the positive electric contact varies according to the equation N A x p = N A 0 T p x p T h 3 2, where N A is an acceptor doping density at the junction end of the second p-type semiconductor doped region where x p = 0; T p ( x p) is a charge carrier temperature at a distance x p measured from the junction end of the second p-type semiconductor doped region towards the positive electric contact; and T h is a charge carrier temperature at the junction end of the second p-type semiconductor doped region where x p = 0, T h being higher than T p. characterised in that the first n-type semiconductor doped region comprises a non-uniform doping profile in which the donor dopant density N D ( x n) at a distance x n measured from the junction end of the first n-type semiconductor doped region towards the negative electric contact varies according to the equation N D x n = N D 0 T n x n T h 3 2, where N D is a donor doping density at the junction end of the first n-type semiconductor doped region where x n = 0; T n (x n) is a charge carrier temperature at a distance x n measured from the junction end of the first n-type semiconductor doped region towards the negative electric contact; and T h is a charge carrier temperature at the junction end of the first n-type semiconductor doped region where x n = 0, T h being higher than T n, and/or in that the second p-type semiconductor doped region comprises a non-uniform doping profile in which the acceptor dopant density N A ( x p) at a distance x p measured from the junction end of the second p-type semiconductor doped region towards the positive electric contact varies according to the equation N A x p = N A 0 T p x p T h 3 2, where N A is an acceptor doping density at the junction end of the second p-type semiconductor doped region where x p = 0; T p ( x p) is a charge carrier temperature at a distance x p measured from the junction end of the second p-type semiconductor doped region towards the positive electric contact; and T h is a charge carrier temperature at the junction end of the second p-type semiconductor doped region where x p = 0, T h being higher than T p.