LONG-TERM OPERATION TESTS OF ORGANIC SOLID-STATE SOLAR CELLS

The long-term operation tests of two types of solid-state organic photovoltaic (OPV) cells, p–n heterojunction type cells and p–i–n junction type cells, were performed. In both cells, a drastic decrease in photocurrent within 1 h was observed in air. This rapid decrease was revealed to be caused by oxygen molecules which act as a electron trap in the electron transporting organic layer. Initial decrease of photocurrent was effectively suppressed under high vacuum (10-7 Torr). In the case of a p–n type cell, the decrease in short-circuit photocurrent was only 15% even under prolonged light irradiation of 260 h.