Improved performance of polymer solar cells by using inorganic, organic, and doped cathode buffer layers

Abstract

The interface between the active layer and the electrode is one of the most critical factors that could affect the device performance of polymer solar cells. In this work, based on the typical poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM) polymer solar cell, we studied the effect of the cathode buffer layer (CBL) between the top metal electrode and the active layer on the device performance. Several inorganic and organic materials commonly used as the electron injection layer in an organic light-emitting diode (OLED) were employed as the CBL in the P3HT:PCBM polymer solar cells. Our results demonstrate that the inorganic and organic materials like Cs 2 CO 3 , bathophenanthroline (Bphen), and 8-hydroxyquinolatolithium (Liq) can be used as CBL to efficiently improve the device performance of the P3HT:PCBM polymer solar cells. The P3HT:PCBM devices employed various CBLs possess power conversion efficiencies (PCEs) of 3.0%-3.3%, which are ca. 50% improved compared to that of the device without CBL. Furthermore, by using the doped organic materials Bphen:Cs 2 CO 3 and Bphen:Liq as the CBL, the PCE of the P3HT:PCBM device will be further improved to 3.5%, which is ca. 70% higher than that of the device without a CBL and ca. 10% increased compared with that of the devices with a neat inorganic or organic CBL.

Amphiphilic Diblock Fullerene Derivatives as Cathode Interfacial Layers for Organic Solar Cells

“…Because of the advantages of low cost, lightweight, flexibility, large-area fabrication, and semitransparency, organic solar cells (OSCs) have been a promising technology for clean and renewable energy conversion. − To improve the power conversion efficiency (PCE), much attention has been given on the interface control, material design, self-assembly of the donor and acceptor phases, and device fabrication. − In addition, the PCE of OSCs has reached over 13%. , One of the strategies is to develop new donor or acceptor materials to enhance the short-circuit current density ( J SC ), open-circuit voltage ( V OC ), and fill factor (FF). , On the other hand, approaches during the device fabrications, such as incorporation of additives, controlling the growth rate of films, and interface modifications, have also been well-studied and exhibited extremely important influences. , The device geometry and interface properties are verified to be two main critical factors toward the preparation of high-performance OSCs. − Interface modifications by placing ultrathin interlayers between the active layer and the electrodes, which may result in a significant lower interface barrier and faster charge transport, have been demonstrated to be an effective approach for the preparation of high-performance OSCs. − …”

Interplay of Interfacial Layers and Blend Composition To Reduce Thermal Degradation of Polymer Solar Cells at High Temperature

“…Here, we study more in details the degradation mechanisms in PSCs under thermal stress related to cathode buffer material and morphology in combination with PTB7:fullerene blends. Among the large choice of EEL materials including organic and inorganic materials, ,, we selected ZnO and calcium (Ca), as both materials were used in the former stability studies of regular device structures using PTB7 donor polymers. , Furthermore, both materials allow EEL processing with varying layer thicknesses and thus morphologies without alternating the device performance strongly. By using first the PTB7:PC 70 BM blend as the thermally stable active layer, we demonstrate that only densely packed ZnO layers generate a high thermal stability, whereas partially covered or porous ZnO layers lead to a strong degradation.…”

“…Here, we study more in details the degradation mechanisms in PSCs under thermal stress related to cathode buffer material and morphology in combination with PTB7:fullerene blends. Among the large choice of EEL materials including organic and inorganic materials, 39,40,46 we selected ZnO and calcium (Ca), as both materials were used in the former stability studies of regular device structures using PTB7 donor polymers. 32,38 Furthermore, both materials allow EEL processing with varying layer thicknesses and thus morphologies without alternating the device performance strongly.…”

Self-assembled monolayer modified copper(I) iodide hole transport layer for efficient polymer solar cells

“…[1][2][3][4][5] In recent years, numerous strategies have been utilized to enhance the performance of PSCs, including the synthesis of efficient photoactive materials, [6,7] the modification of film morphology, [8,9] and the reasonable selection of transport layers. [10][11][12][13] Consequently, the power conversion efficiency (PCE) of PSCs has been significantly improved, and it is worth noting that the values were up to over 12% for nonfullerene polymer solar cells that fabricated by ternary bulk-heterojunction [14] or the molecular regulation of acceptors, [15,16] which will further accelerate the commercial application of PSCs. The widely used structure of PSCs is a sandwich structure of a hole transport layer (HTL), photoactive layer, and electron transfer layer (ETL).…”