Currently, photovoltaic research area is short of solution-processed transparent electrodes, which can replace the widely used vacuum-deposited indium tin oxide (ITO). Here, by employing a two-dimensional metal-organic framework (2D-MOF) Cu-BHT (BHT = benzenehexathiol), a solution-processed transparent electrode with high conductivity over 2500 Scm⁻¹ and high transmittance of 82% is developed. Three classic photovoltaic solar cells (perovskite solar cells, quantum dots solar cells and organic solar cells) are fabricated on both glass and flexible polyimide (PI) substrates with this Cu-BHT electrode, replacing conventionally used ITO. The performances of all the devices are comparable to their corresponding ones with ITO electrode, indicating the great potential of the Cu-BHT electrode in future low-cost and flexible optoelectronics.