Interlayer for Modified Cathode in Highly Efficient Inverted ITO‐Free Organic Solar Cells

Abstract

Inverted polymer solar cells with a bottom metal cathode modified by a conjugated polymer interlayer show considerable improvement of photocurrent and fill factor, which is due to hole blocking at the interlayer, and a modified surface energy which affects the nanostructure in the TQ1/[70]PCBM blend.

Ethanedithiol Treatment of Solution‐Processed ZnO Thin Films: Controlling the Intragap States of Electron Transporting Interlayers for Efficient and Stable Inverted Organic Photovoltaics

“…The champion device has a remarkable FF of 0.72 and a PCE of 6.3%, which is the record efficiency for the inverted devices based on the TQ1: fullerene system to date. [21,[45][46] In contrast, the average PCE for control devices with P-ZnO films, 5.0%, is much lower. Regarding the device stability, when the devices were either stored in dark or tested upon continuous light illumination, a similar trend that the devices with E-ZnO ETLs are much better than the control devices with P-ZnO ETLs was observed (Figure 6b).…”

“…From the normalized absorption and emission spectra shown in Figure S9, almost identical CT emission and EQE features of the two devices indicate that EDT treatment caused negligible influences on the donor-acceptor interfacial areas. [45] These characterizations indicate that the improved device performance of the TQ1 devices arise from the EDT treatment of the ZnO nanocrystal ETLs. This result leads us to conclude that the E-ZnO films can be applied to improve the performance of inverted devices based on donor materials with different electronic structures.…”

Simple experimental test to distinguish extraction and injection barriers at the electrodes of (organic) solar cells with S-shaped current–voltage characteristics

“…[20] an inverted geometry [21] is presented with the layer sequence glass substrate/metal cathode (80 nm)/TQ1:PCBM (80 nm)/PEDOT anode. Whereas the reference solar cell with Ti/Al(80 nm)/Ti(2 nm) cathode shows good performance (fill factor of 0.53) [20], the device without the titanium interlayer exhibits a huge S-kink despite similar work functions [22] of Al and Ti [ Fig. 4(a)].…”

Effects of ultraviolet soaking on surface electronic structures of solution processed ZnO nanoparticle films in polymer solar cells

“…7,8 The inverted device features a low work function interlayer e.g. a transition metal oxide (TiOx, ZnO), 9, 10 conjugated polymer (PFN, PFNBr), [11][12][13] or insulator (PEIE) 14 coated on ITO that acts as the bottom cathode and an airstable high work function metal or metal oxide e.g. Au and MoOx as the top anode.…”