The OP770D from TT Electronics is a Phototransistor with Collector Emitter Voltage (Breakdown) 30 V, Collector-Dark Current 100 nA, Collector Emitter Voltage(Saturation) 0.40 V, Emitter Collector Voltage(Breakdown) 5 V, On-State Collector Current 0.85 to 7 mA. More details for OP770D can be seen below.