Trivalent erbium (Er3+) and erbium-yttribium (Er3+/Yb3+) co-doped Y2CaZnO5 (YCZ) nanophosphors were synthesized via Sol-Gel combustion method and applied as photon up-converter in dye sensitized solar cell (DSSC) and studied for their photovoltaic properties. A bright green and green-red up-conversion emission is observed upon an excitation of 980 nm in Er3+:YCZ and Er3+/Yb3+:YCZ nanophosphors, respectively which indicates the possibility of using these phosphors for light harvesting applications. The prepared Er3+ and Er3+ / Yb3+ co-doped YCZ nanophosphors were incorporated in TiO2 based DSSC to form the composite photoelectrode and studied the power conversion efficiency (PEC). With the incorporation of Er3+ and Er3+/Yb3+ co-doped YCZ nanophosphors in the DSSC resulted in the enhanced PCE of 6.01% and 7.21% using durable methoxypropionitrile (MPN) and volatile acetonitrile (AcN) based electrolytes, respectively. The PCE values obtained for the studied compounds are found to be either comparable or better than the other reported compounds used for the light harvesting. An enhanced photocurrent (Jsc) of 12.44 and 13.28 mA/cm(2), for Er3+:YCZ and Er3+/ Yb3+:YCZ nanophosphors based DSSC, respectively was observed under AM1.5 G light due to the better photon conversion efficiency of the nanophosphor. The detailed up-conversion (UC) mechanism responsible for the enhanced PCE properties were discussed in detail and the results were compared with similar phosphor systems.