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To produce electricity via photothermoelectric effects, single-walled carbon nanotubes (SWCNT)-thermoelectric generators (TEGs) featuring different Seebeck coefficient distributions across pn-junctions are fabricated using vacuum filtration. In general, it is difficult to regulate the patterning area with wet processes as the dispersion tends to diffuse laterally into the SWCNT sheet. However, we modify the conditions of vacuum filtration, and the change rates of Seebeck coefficient across the pn-junction can be controlled from 2.5 to 8.3 μV/(K·mm). Temperature gradients are generated in the SWCNT-TEGs when artificial sunlight is applied to irradiated and non-irradiated areas. The SWCNT-TEG with a steep Seebeck coefficient distribution (8.3 μV/(K·mm)) exhibits at an output voltage of 1.5 mV, which is three times higher than that of the SWCNT-TEG with gradual Seebeck coefficient distribution. These results lead to improve the performance of SWCNT-TEGs for energy harvesting. [Display omitted] • Photothermoelectric effects have been investigated using SWCNT films. • Flexible SWCNT-TEGs with a pn-junction were prepared by vacuum filtration. • Rates of change of the Seebeck coefficient across the pn junction can be controlled. • SWCNT-TEG with a steep Seebeck coefficient distribution exhibits high output voltage. • The results lead to improved performance of SWCNT TEGs for energy harvesting. [ABSTRACT FROM AUTHOR]