A comparative analysis of the optoelectronic performance of conventional and inverted design organic photodetectors

In this report, we present the comparison of the optoelectronic performance of conventional and inverted organic photodiodes (OPDs) based on the blended active layer of p-type poly (3-hexylthiphene) (P3HT) and n-type fullerene C70. The absorption and Raman studies of the blend film confirm the presence of both the constituents in prepared blends. The inverted design OPD demonstrates large photocurrent, responsivity, and detectivity than conventional OPD. The difference in the observed performances is explained by dark current and impedance spectroscopy (IS) analysis. The higher performance observed in inverted design is attributed to the improvement in charge extraction and collection, which is possibly resulting from the favorable vertical phase separation in the P3HT:C70 blends. Higher current levels under dark condition along with lesser ideality factor observed in the case of inverted OPD is in good agreement with the vertical morphology modification. The IS analysis also validate that the improved charge transport and collection enhances the performance of inverted design OPD. •Effect of device geometry on optical performance of OPDs was investigated.•Inverted device exhibits higher performance than standard device. .•High performance in inverted OPD is attributed to improved charge collection.•Correlation between optoelectronic performance and IS parameters were established.