For this purpose, we made another set of inverted solar cells based on P3HT:ICBA with the configuration ITO/ZnO:Cs2CO3/P3HT:ICBA/PEDOT:PSS/Al. As a reference, solar cells without interface modification were also fabricated. Figure 5b shows the J-V characteristics of P3HT:ICBA-based find more devices with two different structures. As mentioned in the ‘Experimental’ Section, these two different types of structures are ITO/ZnO/P3HT:ICBA/PEDOT:PSS/Al-device C and ITO/ZnO:Cs2CO3/P3HT:ICBA/PEDOT:PSS/Al-device D. As expected, the effective dipole moment created by interface modification shifted the work function of the ITO electrode by nearly 1 eV, thereby reducing the electron injection and improving

the ohmic contact for electron injection with P3HT:ICBA. The inverted solar cells (device A) exhibited a contact energy barrier of typically 2.1 eV due to the work function of ITO (4.8 eV), resulting in Jsc that was slightly lower. As observed in Figure 5b, RG7204 in vitro the reference device exhibits Jsc, Voc, FF, and PCE of about 6.28 mA/cm2, 0.89 V, 60.7%, and 3.40%, respectively. The calculated Rs for this device is around 6,666 ohm. For

device D, the PCE increases from 3.40 to 3.43%. This 0.88% increment in the PCE is attributed to the improvement in FF, where the FF increases from 57.7 to 59.3%. A similar trend in Rs can also be seen in P3HT:ICBA-based device, where the Rs decreases together with the increment of FF. In addition, the performance of inverted solar cells in terms of external quantum efficiency (P3HT:PCBM-based devices) is shown in Figure 5c. Basically, the EQE is defined as the ratio between the generated charge carriers and the incident photons. Device A shows a maximum EQE value of ~51.80%

at the absorption wavelength of ~520 nm. However, the EQE selleck chemicals of device B has outperformed the EQEs of device A, in which it exhibits a maximum of about 55% at ~520 nm of absorption wavelength. The external quantum efficiency of the P3HT:ICBA-based devices with the inverted device geometries are shown in Figure 5d. For inverted reference solar cells (device C), the maximum EQE is 51.51% at 500 nm, where the EQE of device D is 53.05%. These results (device B and device D) further shed the light that the improvement in devices performances is related to interface modification which has modified the work function of the ITO electrode. As mentioned above, the presence of Cs2CO3 have improved the surface area of ZnO:Cs2CO3 and PEDOT:PSS through the good interfacial contact between ZnO:Cs2CO3 layer and ITO layer, and PEDOT:PSS and Al layer, leading to the considerably high EQE. In order to get a better understanding on the stability and lifetime of all fabricated inverted solar cells, we kept all devices in air under ambient condition according to the previously reported ISOS-L-1 procedure [43].