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Recently, considerable progress is achieved in lab prototype perovskite solar cells (PSCs); however, the stability of outdoor applications of PSCs remains a challenge due to the high sensitivity of perovskite material under moist and ultraviolet (UV) light conditions. In this work, the UV photostability of PSC devices is improved by incorporating a photon downshifting layer—SrAl2O4: Eu2+, Dy3+ (SAED)—prepared using the pulsed laser deposition approach. Light‐induced deep trap states in the photoactive layer are depressed, and UV light‐induced device degradation is inhibited after the SAED modification. Optimized power conversion efficiency (PCE) of 17.8% is obtained through the enhanced light harvesting and reduced carrier recombination provided by SAED. More importantly, a solar energy storage effect due to the long‐persistent luminescence of SAED is obtained after light illumination is turned off. The introduction of downconverting material with long‐persistent luminescence in PSCs not only represents a new strategy to improve PCE and light stability by photoconversion from UV to visible light but also provides a new paradigm for solar energy storage.

Perovskite solar cells (PSCs) have attracted extensive attention due to their impressive photovoltaic performance. The quality of the perovskite layer is very critical to achieve high device performance. Here, we explore the partial substitution of PbI by ZnCl in the preparation of CHNHPbI and its effects on perovskite morphology, optical properties, and photovoltaic performance. Consequently, the device with 3% ZnCl shows great improvement in power conversion efficiency (PCE) from 16.4 to 18.2% compared to that of the control device. Moreover, the device is more stable than the control device, with only 7% degradation after aging for 30 days. These results are attributed to the increased grain size, improved film morphology, and reduced recombination loss after the partial substitution of PbI by ZnCl in the perovskite film. This work develops a new approach for morphology control through rational additives in the perovskite film, and paves the way toward further enhancing the device performances of PSCs including PCE and stability.

Organic–inorganic halide perovskite solar cells (PSCs) have emerged as attractive alternatives to conventional solar cells. It is still a challenge to obtain PSCs with good thermal stability and high permanence, especially at extreme outdoor temperatures. This work systematically studies the effects of Bi3+ modification on structural, electrical, and optical properties of perovskite films (FA0.83MA0.17Pb(I0.83Br0.17)3) and the performance of corresponding PSCs. The results indicate that Bi3+ modified PSCs can achieve better thermal stability, photovoltaic response, and reproducibility compared with control cells due to the decreased grain boundaries, enhanced crystallization, and improved electron extraction from perovskite film. As a result, the modified PSC exhibits an optimized power conversion efficiency (PCE) of 19.4% compared with 18.3% for the optimized control device, accompanied by better thermoresistant ability under 100–180 °C and enhanced long‐term stability. The degradation rate of the modified device is reduced by an order of magnitude due to effective structural defect modification in perovskite photoactive layer. It could maintain more than two months at 60 °C. These results shed light on the origin of crystallization and thermal stability of perovskite films, and provide an approach to solve thermal stability issue of PSCs.

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Perovskite solar cells (PSCs) with high efficiency have recently received tremendous attention, but the stability under light irradiation, namely, photostability, of PSCs still represents a major obstacle that must be overcome before their practical applications can be used. The degeneration of perovskite under ultraviolet irradiation from sunlight is a major impacting factor. To solve this problem, in this work we introduce fluorescent carbon dots (CDs), which could effectively convert ultraviolet to blue light in the mesoporous TiO (m-TiO) layer of the traditional PSCs. As a result, CD-based devices exhibit an improved power conversion efficiency (PCE) of 16.4% on average compared to 14.6% for bare devices, and the light stability of CD-based devices is highly enhanced. These devices can maintain nearly 70% of the initial efficiency after 12 h of full sunlight illumination, while the bare devices maintain only 20% of the initial efficiency. This work indicates that fluorescent down conversion based on CDs is a novel and effective approach to improve the performance and photostability of PSCs.

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Organic–inorganic lead halide perovskite solar cells (PSCs) exhibit spectacular changes in the photovoltaic area, but they still face the challenges of full spectral utilization and photostability under continuous light irradiation. The ultraviolet (UV) part in sunlight could induce oxygen vacancy in the mesoporous TiO2 (m-TiO2) layer, resulting in the degradation of perovskite photoactive films and the rapidly decreased device performance. In this work, we demonstrate that an effective luminescent downconversion material, Eu­(TTA)2(Phen)­MAA (ETPM), can be used as an interfacial modifier between the m-TiO2 layer and the perovskite photoactive layer to improve the power conversion efficiency (PCE) from 17.00 to 19.07%. The improved device performance can be ascribed to the effective utilization of incident UV light and reduced carrier recombination. Meanwhile, the conversion of the UV light by ETPM could inhibit the stability loss of the device under irradiation. As a result, the modified PSCs can maintain 86% of their initial value under continuous light soaking for 100 h, higher than that of 40% for the control device. This work indicates that the introduction of the luminescent downconversion material ETPM can successfully improve the PCE and photostability of PSCs.