Temperature and light dependent diode current in high-efficiency solution-processed small-molecule solar cells

Abstract

This paper reports on the detail analysis of the DC electrical and photoelectrical properties of the high-efficient (η=8.01% under standard 100mW/cm2 AM1.5 illumination) small molecule bulk heterojunction (SM BHJ) solar cells p-DTS(FBTTh2)2/PC70BM. In this SM BHJ solar cell, the dark diode current is determined by the multistep tunnel-recombination via interface states at low forward bias (V<0.65V) and the interface state assisted thermionic emission at high forward bias (V>0.65V). The effect of illumination on the diode current was also quantitatively investigated. It was observed a reduced Shockley–Read–Hall recombination via interface states at large forward bias (from the maximum power point to the open-circuit conditions). The expression of the load I–V characteristic of the illuminated high-efficient SM BHJ solar cells was derived in the presence of the light dependent series and shunt resistance.