RESUMO
Semitransparent organic photovoltaics (ST-OPVs), owing to the merits of high power generation, thermal insulation, and aesthetic features, have become a promising candidate for intellectual building- integrated photovoltaic windows. However, the traditional optical evaluation only focuses on the transmission properties and ignores the reflection behaviors. And the lack of quantitative descriptions for array appearance hinders implementation of ST-OPV based large-area modules. To tackle with these issues, an indium tin oxide (ITO)-free optical microcavity architecture into ST-OPVs for achieving high homogeneity in transmittance with controllable reflective appearances through tunning the thickness of individual component layers is introduced. A set of parameters based on optical characteristics of sub-units to provide a quantitative description for the transmittance brightness, transmissive and reflective color purity, and versatility of optical arrays, is further proposed. The optical simulations reveal that reflection modulation from blue to red colors can be realized for devices based on various bulk-heterojunction material systems through regulating the thickness of active layers and antireflection coatings. This work offers a viable design strategy for ST-OPVs toward applications in next-generation smart photovoltaic windows.
RESUMO
2D perovskites based on Formamidinium (FA) hold the potential for excellent stability and a broad absorption range, making them attractive materials for solar cells. However, FA-based 2D perovskites produced via one-step processing exhibit poor crystallinity and random quasi-quantum wells (QWs), leading to subpar photovoltaic performance. In this study, a seed-induced growth approach is introduced employing MAPbCl3 and BDAPbI4 in the deposition of FA-based Dion-Jacobson 2D perovskite films. This method yields high-quality perovskite films as the seeds preferentially precipitate and serve as templates for the epitaxial growth of FA-based counterparts, effectively suppressing the δ phase. Moreover, the epitaxial growth facilitated by uniformly dispersed seeds results in simultaneous crystallization from top to bottom, efficiently mitigating random phases (n = 2, 3, 4 ) induced by the diffusion of organic cations and, in turn, minimizing energy loss. The impact of seed-induced growth on the crystallization and phase distribution of FA-based 2D perovskites is systematically investigated. As a result, the optimized FA-based 2D perovskite solar cell delivers an outstanding efficiency of 20.0%, accompanied by a remarkable fill factor of 0.823. Additionally, the unencapsulated device demonstrates exceptional stability, maintaining 98% of its initial efficiency after 1344 h of storage.
RESUMO
The stability of organic solar cells is a key issue to promote practical applications. Herein, we demonstrate that the device performance of organic solar cells is enhanced by an Ir/IrOx electron-transporting layer, benefiting from its suitable work function and heterogeneous distribution of surface energy in nanoscale. Notably, the champion Ir/IrOx-based devices exhibit superior stabilities under shelf storing (T80 = 56696 h), thermal aging (T70 = 13920 h), and maximum power point tracking (T80 = 1058 h), compared to the ZnO-based devices. It can be attributed to the stable morphology of photoactive layer resulting from the optimized molecular distribution of the donor and acceptor and the absence of photocatalysis in the Ir/IrOx-based devices, which helps to maintain the improved charge extraction and inhibited charge recombination in the aged devices. This work provides a reliable and efficient electron-transporting material toward stable organic solar cells.
