Shen QING (沈 青)

Abstract

Double perovskite quantum dots (QDs) with self‐trapped exciton emission provide an eco‐friendly route to broadband white‐light generation. Yet severe charge losses arising from trap‐mediated recombination and inefficient carrier transport remain major obstacles to their integration into electroluminescent devices. Here, Sb³⁺/Mn²⁺ co‐doped Cs₂NaInCl₆ QD inks are reported that enable the fabrication of defect‐suppressed, conductive QD films with low charge transport and hole‐injection barriers in light‐emitting diode (LED) devices. Sb³⁺/Mn²⁺ co‐doping not only induces white emission but also suppresses cation disorder, leading to near‐unity photoluminescence quantum yield. Moreover, replacing long‐chain ligands with short‐chain 2‐ethylhexanoic acid and 3,3‐diphenylpropylamine chloride enhances the film conductivity by nearly 20‐fold and induces a favorable band alignment with the poly(9‐vinylcarbazole):poly[N,N′‐bis(4‐butylphenyl)‐N,N′‐bis(phenyl)‐benzidine] hole transport layer, hereby reducing the injection barrier by 0.4 eV. These improvements enable an LED external quantum efficiency of 0.91% (0.05 cm²)—the highest reported for double perovskite QDs and nearly 1.3 the previous record. It is anticipated that this work provides a viable route toward overcoming the key limitations of double perovskite electroluminescence and advancing eco‐friendly solid‐state lighting.

Abstract

Developing diverse photovoltaic device architectures is essential not only for improving power conversion efficiency (PCE) but also for enabling seamless integration with other photovoltaic materials in high‐performance tandem configurations. While n‐i‐p architectures have historically dominated the development of PbS colloidal quantum dots (CQDs) solar cells, p‐i‐n counterparts have significantly lagged behind in efficiency, limiting their potential for further advancement. In this work, the advantage of the surface tunability of CQDs is taken by anchoring the classical self‐assembled monolayer (SAM) molecule MeO‐2PACz onto PbS CQDs via ligand exchange, forming a PbS‐SAM bridging‐layer, which is inserted between NiOx/SAM and the CQD active layer, resulting in a NiOx/SAM/PbS‐SAM composite hole transporting layer (HTL). This structure effectively passivates the buried interfacial traps and enhances hole extraction. As a result, a record PCE approaching 14% is achieved, with a certified value of 13.62%, which is not only largely surpassing the previous highest value of 9.70% for p‐i‐n PbS QD solar cells, but also exceeds the current PCE record set by n‐i‐p architectures. Moreover, the p‐i‐n configuration exhibits excellent reproducibility, providing a robust and scalable platform for future applications, particularly as a narrow‐bandgap subcell in monolithic tandem devices with wide‐bandgap materials such as perovskites.

Abstract

Mixed cation quasi‐2D tin iodide perovskites are promising materials for deep‐red to NIR emitting light‐emitting diode (LED) applications. However, phase purity remains the major concern to avoid mixed emissions from two or more wavelengths. This work presents the evolution of pure deep red electroluminescence (EL) centred at ≈700 nm corresponding to the emission of pure n = 2 2D crystalline phase. However, structural and optical studies evidenced the formation of mixed‐phase heterostructures consisting of n = 1, n = 2, and n = ∞ phase (i.e., FASnI₃). It is observed that altering the mixed cation ratio, phase distribution is modified, affecting the EL behavior, causing the observation or absence of the n = 1 2D phase EL emission peak. Selective charge transport and their cascade mechanism illustrates the pure color EL evolution with the support from transient absorption spectroscopic studies. In this regard, a case study is provided along with the supportive rationalities behind the exceptional evolution of pure deep red EL even from the mixed‐phase perovskite, reported for the first time in case of quasi‐2D tin iodide perovskite.

Abstract

This study introduces a multifunctional coordination approach to enhance wide bandgap (WBG) tin (Sn) perovskite solar cells (PSCs) by incorporating a naturally derived Vitamin H (Biotin) complex into the perovskite precursor. The Biotin complex exhibits strong chemical interaction with Sn²⁺ via its ureido ring (CO, NH), valeric acid chain (COO⁻), and tetrahydrothiophene (SC) functionalities. This multidentate interaction further helps to regulate crystal growth kinetics, resulting in compact, pinhole‐free films with enhanced surface homogeneity. Furthermore, Biotin effectively passivates uncoordinated Sn sites, mitigates Sn²⁺ oxidation, and suppresses antisite defects, thereby reducing non‐radiative recombination and ion migration. As a result, the optimized device demonstrates a record‐high power conversion efficiency of 12.8% (independently certified at 12.5%) and an open‐circuit voltage (V_oc) of 1.03 V for WBG Sn PSCs. Notably, the device exhibits outstanding ambient stability, retaining almost 80% of its initial efficiency after 1460 h of storage without encapsulation, highlighting the potential of the Biotin complex for high‐performance and durable lead‐free perovskite photovoltaics.

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