Copper(I) thiocyanate (CuSCN) is rising to prominence as a hole‐transporting semiconductor in various opto/electronic applications. Its unique combination of good hole mobility, high optical transparency, and solution‐processability renders it a promising hole‐transport layer for solar cells and p‐type channel in thin‐film transistors. CuSCN is typically deposited from sulfide‐based solutions with diethyl sulfide (DES) being the most widely used. However, little is known regarding the effects of DES on CuSCN films despite the fact that DES can coordinate with Cu(I) and result in a different coordination polymer having a distinct crystal structure when fully coordinated. Herein, the coordination of DES in CuSCN films is thoroughly investigated with a suite of characterization techniques as well as density functional theory. This study reveals that DES directly affects the microstructure of CuSCN by stabilizing the polar crystalline surfaces via the formation of strong coordination bonds. Furthermore, a simple antisolvent treatment is demonstrated to be effective at modifying the microstructure and morphology of CuSCN films. The treatment with tetrahydrofuran or acetone leads to uniform films consisting of CuSCN crystallites with high crystallinity and their surfaces passivated by DES molecules, resulting in an increase in the hole mobility from 0.01 to 0.05 cm2 V−1 s−1.

Cyanobacteria change the quantity and/or quality of their pigment-protein complexes in response to light conditions. In the present study, we analyzed excitation relaxation dynamics in the cyanobacterium, Arthrospira (Spirulina) platensis, grown under lights exhibiting different spectral profiles, by means of steady-state absorption and picosecond time-resolved fluorescence spectroscopies. It was found that F760, which is the PSI red-chlorophyll characteristic of A. platensis, contributes to slower energy-transfer phase in the PSI of A. platensis. Excitation energy transfers in phycobilisome and those from PSII to PSI were modified depending on the light quality. Existence of quencher was suggested in PSI of the blue-light grown cells. Phycobilisomes in the green-light grown cells and the far-red-light grown cells transferred excitation energy from phycobilisome to chlorophyll without loss of energy. In these cells, excitation energy was shared between two photosystems. Fast energy transfer was established in phycobilisome under the yellow-light condition where only the phycobilisome can absorb the cultivation light. Differences in light-harvesting and energy-transfer processes under different cultivation-light conditions are discussed. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.

The light-harvesting mechanisms in the three strains of Prochlorococcus marinus, CCMP1986, CCMP1375, and CCMP2773, grown under blue and red light-emitting diodes (LEDs) at two intensity levels were investigated. The blue LED was divinyl chlorophyll b (DV-Chl b) selective and the red LED was DV-Chl a selective. Under the red LED, the relative amount of DV-Chl b in CCMP1375 and CCMP2773 decreased and the relative amount of zeaxanthin increased in CCMP1375. Furthermore, the pigment composition of cells of CCMP1375 grown under red LED was remodified when they were transplanted under the blue LED. Picosecond-time-resolved fluorescence of the LED-grown Prochlorococcus was measured, and the excitation-energy-transfer efficiency between DV-Chl a did not significantly change for the different LED colors or intensities; however, a change in the pigment composition of the DV-Chl b-rich strains (CCMP1375 and CCMP2773) was observed. It appears that peripheral antenna responds to light conditions, with small modifications in the photosystems.

The marine cyanobacterium Prochloron is a unique photosynthetic organism that lives in obligate symbiosis with colonial ascidians. We compared Prochloron harbored in four different host species and cultured Prochlorothrix by means of spectroscopic measurements, including time-resolved fluorescence, to investigate host-induced differences in light-harvesting strategies between the cyanobacteria. The light-harvesting efficiency of photosystems including antenna Pcb, PS II-PS I connection, and pigment status, especially that of PS I Red Chls, were different among the four samples. We also discuss relationships between these observed characteristics and the light conditions, to which Prochloron cells are exposed, influenced by distribution pattern in the host colonies, presence or absence of tunic spicules, and microenvironments within the ascidians' habitat.

Prochlorococcus, a unique marine picocyanobacterium, contains the divinyl- (DV-) type chlorophylls (Chls), DV-Chl a and DV-Chl b, as its photosynthetic pigments. We comprehensively investigated the light-harvesting mechanisms in three strains of Prochlorococcus marinus (P. marinus) at physiological temperature (293 K) by ultrafast time-resolved fluorescence (TRF), steady-state fluorescence, and absorption measurements. These strains differ in their relative amounts of DV-Chl a, DV-Chl b, and carotenoids and in the pigment coupling conditions. All of the strains showed ultrafast excitation energy transfer from DV-Chl b to DV-Chl a, and the low-light-adapted strains, P. marinus CCMP1375 and CCMP2773, exhibited relatively higher DV-Chl b contents than P. marinus CCMP1986. It appears that carotenoid is another important antenna pigment, especially in the low-light-adapted strains (CCMP1375 and CCMP2773), that transfers the excitation energy to lower-energy DV-Chl a.