Nitrogen-Mediated Growth of Silver Nanocrystals to Form UltraThin, High-Purity Silver-Film Electrodes with Broad band Transparency for Solar Cells

Abstract

Controlling the shape and crystallography of nanocrystals during the early growth stages of a noble metal layer is important because of its correlation with the final layer morphology and optoelectrical features, but this task is unattainable in vapor deposition processes dominated by artificially uncontrollable thermodynamic free energies. We report on experimental evidence for the controllable evolution of Ag nanocrystals as induced by the addition of nitrogen, presumed to be nonresidual in the Ag lattice given its strong float-out behavior. This atypical formation of energetically stable Ag nanocrystals with significantly improved wetting abilities on a chemically heterogeneous substrate promotes the development of an atomically flat, ultrathin, high-purity Ag layer with a thickness of only 5 nm. This facilitates the fabrication of Ag thin-film electrodes exhibiting highly enhanced optical transparency over a broad spectral range in the visible and near-infrared spectral range. An Ag thin-film electrode with a ZnO/Ag/ZnO configuration exhibits an average transmittance of about 95% in the spectral range of 400−800 nm with a maximum transmittance of over 98% at 580 nm, which is comparable with the best transparency values so far reported for transparent electrodes. This degree of optical transparency provides an excellent chance to improve the photon absorption of photovoltaic devices employing an Ag thin film as their window electrode. This is clearly confirmed by the superior performance of a flexible organic solar cell with a power conversion efficiency of 8.0%, which is far superior to that of the same solar cell using a conventional amorphous indium tin oxide electrode (6.4%).

Using Dual Microresonant Cavity and Plasmonic Effects to Enhance the Photovoltaic Efficiency of Flexible Polymer Solar Cells

“…It is difficult to demonstrate the incorporation of Ag@SiO 2 -NPs caused the enhanced light absorption directly by one characterization. However, it can be proved by the photoluminescence (PL) measurement of PTB7-Th film with 1 wt% Ag@SiO 2 -NPs and pure PTB7-Th film [40,54]. The reasons that PL measurement verifies the light enhancement can be illustrated by Figure 7a.…”

“…For devices with Ag (O) layers more than 9.0 nm, i.e., 12 and 15 nm, the photovoltaic performances decrease greatly, mainly due to the greatly decreased photocurrent, which are induced by the reduced total transmittance value. The photovoltaic performances can be verified by the EQE measurement, for instance, by calculating EQE curve area, the calculated Jsc can be obtained [46,53,54]. Figure 5b shows the EQE curves of devices with various Ag (O) thickness, and from the result, it can be seen that the device with 6.0 nm Ag (O) layer shows highest EQE value, the calculated Jsc is 17.45 mA cm −2 , which in accordance with that of value obtain by I−V measurement.…”

Manipulation of thin metal film morphology on weakly interacting substrates via selective deployment of alloying species

“…Vapor-based synthesis of thin noble-metal films and nanostructures on oxides and van der Waals materials is a key step for fabricating heterostructure devices in the areas of nanoelectronics, 1,2 biosensing, 3 catalysis, 4,5 energy saving, 6 and energy conversion. [7][8][9] The performance of these devices depends crucially on the metal film morphology; in some cases, flat two-dimensional (2D) metal-layers that fully wet the underlying substrate are required, while in other cases the objective is to decorate the substate with arrays of three-dimensional (3D) metal nanostructures with well-defined sizes and shapes. 1,2 Achieving such control over the metal film morphology is challenging, as weak interaction (i.e., bond strength) at the interface forming between most metals and oxides or van der Waals materials provides a strong driving force for uncontrolled formation of 3D metal island agglomerates on the substrate surface.…”

Highly Efficient and High Peak Transmittance Colorful Semitransparent Organic Solar Cells with Hybrid-Electrode-Mirror Microcavity Structure

“…This type of semitransparent OSCs (ST-OSCs) has extensive application in the fields of photovoltaic transparent windows, photovoltaic building integration, and photovoltaic automotive glass because of two merits: photovoltaic power generation and light transparency in specific visible bands. Therefore, ST-OSCs have become a new topic to be studied intensely. − …”

“…Over the past decade, researchers have made great efforts to optimize PCE, transparency, and chromaticity (such as color, color rendering index, etc.,) of ST-OSCs. These research studies mainly focus on developing new transparent electrodes, − synthesizing highly efficient receptor/donor materials, − and constructing optical structure to manipulate the optical field. − With these efforts, efficiency of ST-OSCs has exceeded 10% with moderate transmission. , In this type of ST-OSCs, device color is mainly determined by the absorption spectra of the active layer, which are directly related to the bandgap of donor and acceptor materials. Unfortunately, because of the broad absorption spectra of organic materials, the color of ST-OSCs is usually rendered nearly neutral and colorful ST-OSCs with high purity are difficult to fabricate.…”