Improved Reliability of Small Molecule Organic Solar Cells by Double Anode Buffer Layers

Abstract

An optimized hybrid planar heterojunction (PHJ) of small molecule organic solar cells (SM-OSCs) based on copper phthalocyanine (CuPc) as donor and fullerene (C 60 ) as acceptor was fabricated, which obviously enhanced the performance of device by sequentially using both MoO 3 and pentacene as double anode buffer layers (ABL), also known as hole extraction layer (HEL). A series of the vacuum-deposited ABL, acting as an electron and exciton blocking layer, were examined for their characteristics in SM-OSCs. The performance and reliability were compared between conventional ITO/ABL/CuPc/C 60 /BCP/Ag cells and the new ITO/double ABL/CuPc/C 60 /BCP/Ag cells. The effect on the electrical properties of these materials was also investigated to obtain the optimal thickness of ABL. The comparison shows that the modified cell has an enhanced reliability compared to traditional cells. The improvement of lifetime was attributed to the idea of double layers to prevent humidity and oxygen from diffusing into the active layer. We demonstrated that the interfacial extraction layers are necessary to avoid degradation of device. That is to say, in normal temperature and pressure, a new avenue for the device within double buffer layers has exhibited the highest values of open circuit voltage (V oc ), fill factor (FF), and lifetime in this work compared to monolayer of ABL.

Improving Performance and Lifetime of Small-Molecule Organic Photovoltaic Devices by Using Bathocuproine–Fullerene Cathodic Layer

“…However, the device lifetime continuously decreased with the operating time. 52,61,62 A possible reason for the decrease in the lifetime is the use of the BCP buffer layer, which easily crystallizes at an ambient temperature even when the device is stored in a vacuum without being exposed to the atmosphere. 10,65−67 Although mixed buffer layers have been proposed in the literature, the device lifetime has yet to be investigated.…”

“…The aforementioned results show that using a 24 nm BCP:C 60 buffer layer improves the performance, enabling manipulation of the optical properties and increasing the charge collection efficiency. In previous studies, inserting anodic buffer layers at the anode/organic interface has increased stability. ,− Without the anodic buffer layers, oxygen in the ITO may diffuse into the organic layer and penetrate the fullerene, which easily reacts with oxygen . The reduced conductivity caused by the reaction of oxygen and fullerene primarily contributes to a short device lifetime .…”

The Effect of Solvents on the Performance of CH3NH3PbI3 Perovskite Solar Cells

“…At present, PSC structures can be mainly divided into two species: conventional structures, which originated from the concept of dye-sensitized solar cells [4][5][6][7], and inverted structures, which originated from the concept of organic solar cells (OSCs) [8][9][10][11][12][13][14]. Conventional structures are composed of a transparent conductive oxide (TCO) substrate/electron transport layer (ETL)/perovskite layer/hole transport layer (HTL)/anode, whereas inverted structures are composed of a TCO substrate/HTL/perovskite layer/ETL/cathode.…”

Revealing the Interfacial Photoreduction of MoO3 with P3HT from the Molecular Weight-Dependent “Burn-In” Degradation of P3HT:PC61BM Solar Cells

“…With that, an interfacial photochemical reaction between P3HT and MoO 3 is then proposed as shown in Figure , where the direct connection of P3HT with MoO 3 leads to the formation of Mo­(V) under light illumination, which increases interfacial charge recombination and consequently reduces the V OC and FF of the cells. − These results suggest that new interfacial materials that do not react with conjugated polymer highly need to achieve highly stable polymer solar cells.…”