Semitransparent Solar Cells with Ultrasmooth and Low-Scattering Perovskite Thin Films

Abstract

Semitransparent solar cells can be applied to photovoltaic windows, which harvest light from both sides. Here we report that the visual transparency of perovskite solar cells can be improved by suppressing the optical scattering at the perovskite layer, through making the surface ultrasmooth, without undue reduction of the perovskite thickness and efficiency. Ultrasmooth perovskite films prepared by a short spinning with vacuum drying method, mean roughness of which is 6 nm or lower, exhibit suppressed scattering (<2%) and high visual transparency. The power conversion efficiency (PCE) of 14.26% is achieved with a thick Ag top electrode (100 nm). A semitransparent cell with a thin Ag top electrode (10 nm) coated with MoO3 (20 nm) exhibits scattering of <1% and PCE of 11.0 and 8.7% for the front and back incidence, respectively. The ultrasmooth and compact preovskite layer leads also to fast photocurrent responses with negligible or sufficiently small hysteresis.

Emerging Novel Metal Electrodes for Photovoltaic Applications

“…Recently, the strategy of molecule treatment on the substrate or the metal oxide layer, such as (3-mercaptopropyl) trimethoxysilane (MPTMS), oxygen plasma treated ormoclear, 11-mercapto-undecanoic acid, polyethyleneimine (PEI), polyallylamine, poly(N-vinylcarbazole), and bathocuproine (BCP) can greatly improve the wetting of metal film on the substrate, by taking advantage of the strong bonding between metal atoms and the functional groups of thiol or amine in the molecules to minimize the coalesce of metal atoms into clusters. [339][340][341][342][343][344][345][346][347][348] Sub-10 nanometer metal film with smooth and continuous surface can be achieved through this approach, which enables the high transparency and conductivity of the electrode. In addition, the work function of the electrode can also be altered due to the metal film modification by the dipole layer of small molecules, which is advantageous to the performance of optoelectronic devices.…”

“…Combined the strategies discussed in Section 2.3 for achieving high transparent and conductive electrode, different kinds of transparent electrode with multilayer structure have successfully demonstrated as the top electrodes for PVSCs. [344,346,[421][422][423][424][425][426][427] Table 1 briefly summarizes the structures of ultrathin metal film based transparent electrodes and the performance of single junction PVSCs by using them as the transparent top electrode. Meanwhile, the application of metal NW network and metal mesh in PVSCs as the transparent top electrode can also be achieved through lamination method due to the solvent free process (see Figure 9a,b).…”

Semi-transparent Perovskite Solar Cells Developed by Considering Human Luminosity Function

“…The optical scattering 18 and the human luminosity factor 19 should also be taken into account in fabricating semi-transparent PVSCs. Strong scattering from the rough surface of a perovskite layer hinders the visual transparency even if the transmittance measured is high.…”

“…Strong scattering from the rough surface of a perovskite layer hinders the visual transparency even if the transmittance measured is high. Nanoscale smoothing of the perovskite surface suppresses the scattering and leads to good visual transparency 18 . The luminosity factor, namely human visual sensitivity to light, is shown in Fig.…”

Materials chemistry approaches to the control of the optical features of perovskite solar cells

“…Gas-assisted liquid processing also offers the opportunity to prepare smooth and continuous thin layers of ABX 3 perovskites to control the transparency. 91,96 The lack of roughness of the layers contributes to avoiding diffuse light scattering, improving the optical quality of the solar cells. Fig.…”