A semiconductor image sensor includes a substrate and an isolation insulating pattern having a trench therein, on the substrate. A lower transparent electrode is provided within the trench. This lower transparent electrode includes a first layer and a different second layer on the first layer. An organic photoelectric layer is provided on the lower transparent electrode, and an upper transparent electrode is provided on the organic photoelectric layer. The first layer may contact a bottom and a side surface of the trench, and may have a seam therein, which is at least partially filled by a portion of the second layer. The first layer may have a higher light transmission efficiency relative to the second layer and a lower electrical resistance relative to the second layer.