Performances of Au NP Devices

Four device structures have been investigated [56] as follows:

Device A: (control): ITO/PEDOT:PSS/P3HT:PCBM/LiF (1 nm)/Al (100 nm) Device B: ITO/PEDOT:PSS? Au NPs/P3HT:PCBM/LiF (1 nm)/Al (100 nm) Device C: ITO/PEDOT:PSS/P3HT:PCBM? Au NPs/LiF (1 nm)/Al (100 nm) Device D: ITO/PEDOT:PSS? AuNPs/P3HT:PCBM? Au NPs/LiF (1 nm)/Al (100 nm)

J-V characteristics of the four OSC device structures with Au NPs incorporated into different organic layers are shown in Fig. 8.19, and the photovoltaic param­eters are listed in Table 8.2.

We observe that the incorporation of Au NPs into either the PEDOT:PSS layer (Device B) or the active layer (Device C) or improves PCE from 3.16 (control Device A) to 3.61 and 3.44 %, respectively. Interestingly, the simultaneous incorporation of Au NPs into both layers results in a further improvement of average PCE to 3.85 %, which corresponds to *22 % increment from the control Device A. In all cases, the increases in PCE are results of improvements in Jsc and FF, while the VOC is unchanged. Notably, when incorporating Au NPs into both PEDOT:PSS and active layer simultaneously, the series resistance (RS) reduces obviously from 3.05 (Device A) to 1.93 Q-cm2 (Device D), contributing to a remarkable increase of FF from 61.92 to 65.00 %. To study the origins of PCE improvement, we first separately study the effects of NPs when incorporated into either the PEDOT:PSS or P3HT:PCBM layer, which is followed by discussions on PCE improvement when NPs are incorporated in all polymer layers.