In current switchable PV technology there is a fundamental tradeoff between power conversion and visible transmittance.
The aim of SwitchGlaze is to “Demonstrate a cohesive switchable PV window that adapts its absorption properties to solar conditions without pairing separate electrochromic and PV devices”
The complexed state is stabilized by weak hydrogen bonds between methylamine CH3NH2 and the organic sublattice of methylamonium lead iodide CH3NH3PbI3, and its conversion to the dissociated state is dependant on the partial pressure (P) of methylamine CH3NH2 gas (g) and temperature (T) of the solid (s) phase.
Bleached to Colored:
Solar photothermal heating dissociates CH3NH2 from the CH3NH3PbI3 layer
Visibly transparent to dissociated, visibly opaque
Photocurrent generated in colored state
Colored to Bleached:
Device sealed in a closed atmosphere of dilute (2%) CH3NH2 gas in argon
Returns to its complexed, bleached state upon removing solar irradiation and cooling to re-form CH3NH3PbI3•xCH3NH2
Scientists demonstrated:
Solar energy conversion efficiencies as high as 11.3% in the colored state
High visible light transmittance (68%) in the bleached state
Reversible switching over 20 cycles
Low switching temperature accessible by solar irradiation in most climates
Fast switching time (less than 3 min).
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