Lead contamination and intrinsic instability of lead-based perovskite materials greatly limit their application in reliable and scalable manner, and the development of efficient and stable lead-free alternatives is highly desirable....
Poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] (PTAA) represents the state‐of‐the‐art hole transport material (HTM) in inverted perovskite solar cells (PSCs). However, unsatisfied surface properties of PTAA and high energy disorder in the bulk film hinder the further enhancement of device performance. Herein, a simple small molecule 10‐(4‐(3,6‐dimethoxy‐9H‐carbazol‐9‐yl)phenyl)‐3,7‐bis(4‐vinylphenyl)‐10H‐phenoxazine (MCz‐VPOZ) is strategically developed for in situ fabrication of polymer hole conductor (CL‐MCz) via a facile and low‐temperature cross‐linking technology. The resulting polymer CL‐MCz offers high energy ordering and improved electrical conductivity, as well as appropriate energy‐level alignment, enabling efficient charge carrier collection in the devices. Meanwhile, CL‐MCz synchronously provides satisfied surface wettability and interfacial functionalization, facilitating the formation of high‐quality perovskite films with fewer bulk iodine vacancies and suppressed carrier recombination. Significantly, the device with CL‐MCz yields a champion efficiency of 23.9% along with an extremely low energy loss down to 0.41 eV, which represents the highest reported efficiency for non‐PTAA‐based polymer HTMs in inverted PSCs. Furthermore, the corresponding unencapsulated devices exhibit competitive shelf‐life stability under various operational stressors up to 2500 h, reflecting high promises of CL‐MCz in the scalable PSC application. This work underscores the promising potential of the cross‐linking approach in preparing low‐cost, stable, and efficient polymer HTMs toward reliable PSCs.
The polarization of polar domain in ferroelectric materials is orientated and reversed with the alternating electric field, and the hysteresis loops of polarization-electric field (P-E) and strain-electric field (S-E) are observed. For electrocaloric (EC) effect, the temperature change with the application and removal of electric field is also attributed to the change of polarization with the applied field. In most reports about EC, the temperature change is shown as an abrupt jump or slump due to the applied electric field that is a pulsed wave. Obviously, it is impossible to observe the hysteresis loop of EC. In our research, both sine wave and pulsed wave electric field are applied to samples in direct measurement, and temperature-electric field hysteresis loop (T-E) is observed only in measurement of sine wave. The T-E hysteresis loop displays a shape of butterfly, just like the shape of S-E. The electric field dependence of EC is also given. The obtained results will be helpful for us to know the electrocaloric effect further.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.