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This chapter gives an extensive overview into the nature of the environment that luminaires and thus LEDs are subjected to during the event of a lightning stroke. Direct lightning stroke almost always results in instant damage for low-voltage connected devices, except in “extraordinary circumstances” where random components may survive. This is usually not a subject for debate and is not the subject of this monograph. Indirect consequences of lightning strokes, however, can be effectively mitigated as described. This chapter also delves into a realistic expected overvoltage levels for two typical systems, overhead lines and insulated cables, as obtained from lightning studies on a power network supplying power to LED devices and thus justifies the recommendations by several standards. In addition, it shows the importance of an often neglected device—MOV in mitigating attendant surges due to lightning to a level that can be withstood by LEDs and associated devices.

The penetration of solid state lighting applications is due to the promise of a low-cost reliable solution by means of application of low- and mid-power LEDs. These LED packages are manufactured by making use of new processes and materials which in principle introduces a series of known and unknown failure modes. Corrosion is a specific failure mode which limits the lifetime, and hence manufacturers realize that their package integrity needs to be improved. This chapter describes the sensitivity to corrosion of LED packages. In the first part, an introduction to chemical incompatibility is given. In the second part, different sources of corrosion are distinguished. The construction of LED packages and their vulnerability to corrosion is described in the third part. In the fourth part of this chapter, testing methods are reviewed and their effectiveness to simulate real-life conditions. A series of experimental setups is used to explore the behavior of LED packages in contaminated environments. A combined experimental–theoretical approach is used to describe the performance in certain conditions of pollution. This will be covered in the fifth part. The last part describes a list of classes of chemicals, often found in electronics and construction materials for luminaires that may affect LED performance and for this reason should be avoided for the design of SSL solutions.

Traditional lighting is focused on the prevention of hardware failures. With the trend toward controlled and connected systems, other components will start playing an equal role in the reliability of it. Here reliability need to be replaced by availability, and other modeling approaches are to be taken into account. Software reliability can only be covered by growth models, with the Goel-Okumoto as a promising candidate. System prognostics and health management is the next step to service the connected complex systems in the most effective way possible. In this chapter we highlight the next frontiers that will need to be taken in order to move the traditional lighting catastrophic failure thinking into a thinking more toward new ways how system (degraded) functions can fail or be compromised.

In the past 4 years we have witnessed a change in quality and reliability to make the marked introduction of solid-state lighting (SSL) successful. LED penetration levels have reached values of 10–30%, depending on the application. The number and variety of LED packages and, thus, associated LED-based products, have significantly increased in the past years. Consequently, new processes and new materials are introduced which will introduce a new series of new and unknown failure modes in SSL products. The understanding of these failure modes is better understood, and the number has grown to beyond 50. The fingerprint is changing to failures that are due to interactions between components. First exercises with system level acceleration tests are presented, but it is important to derive acceleration models for these tests. Advanced reliability prediction capabilities are needed including algorithms and tools that couple the multi-physic and multiscale behavior of the SSL failure modes. The shift toward services will force the lighting industry to develop these capabilities in order to better address lifetime and reliability. Connected lighting will bring big data from live connections that can be used to determine the degradation level of the system. Both trends, service and connected, will bring yet another huge change in mind-set in the lighting industry when in concerns reliability: detailed understanding of failure mechanisms, usage scenarios, technology, and design will come together.

Commercial claims for LED-based products in terms of lumen maintenance are fully based on TM-21 extrapolations using LM-80 data. This chapter indicates that there may be a risk in doing this as TM-21 only relies on the behavior of the average LED degradation, instead of taking into account the degradation of all individual LEDs. Therefore, we propose a more profound statistical approach in order to make the appropriate step from TM-21 extrapolation to lumen maintenance on a product level. This is needed as some commercial claims are based on 10 years of warranty and some service bids provide periods of 20–25 years of operation. This chapter reviews the different approaches currently available to perform lumen maintenance extrapolations.

6-Phenyl-2,2′-bipyridine linked pyrene and anthracene were synthesized and their photophysical properties were measured in different solvents with different polarity. 4-Pyren-1″-yl-6-phenyl-2,2′-bipyridine (Ppbpy) showed significant solvent-dependent properities while 4-anthracen-yl-9″-yl-6-phenyl-2,2′-bipyridine (Apbpy) displayed solvent-independence, although they had similar molecular structure. Because of different twist angle between the arene and aryl-bipyridine, Ppbpy displayed intermixing behaviors of local excited state (1La and 1Lb) and intramolecular charge transfer (ICT), but Apbpy only showed the properties of local excited state 1La.