Banana-shaped electron acceptors with an electron-rich core fragment and 3D packing capability

The emergence of Y6-type nonfullerene acceptors has greatly enhanced the power conversion efficiency(PCE)of organic solar cells(OSCs).However,which structural feature is responsible for the excellent photovoltaic performance is still under debate.In this study,two Y6-like acceptors BDOTP-1 and BDOTP-2 were designed.Different from previous Y6-type acceptors featuring an A–D–Aʹ–D–A structure,BDOTP-1,and BDOTP-2 have no electron-deficient Aʹfragment in the core unit.Instead,there is an electron-rich dibenzodioxine fragment in the core.Although this modification leads to a marked change in the molecular dipole moment,electrostatic potential,frontier orbitals,and energy levels,BDOTP acceptors retain similar three-dimensional packing capability as Y6-type acceptors due to the similar banana-shaped molecular configuration.BDOTP acceptors show good performance in OSCs.High PCEs of up to 18.51%(certified 17.9%)are achieved.This study suggests that the banana-shaped configuration instead of the A–D–Aʹ–D–A structure is likely to be the determining factor in realizing high photovoltaic performance.

Side chain engineering on D18 polymers yields 18.74%power conversion efficiency

Donor-acceptor(D-A)conjugated copolymers contain-ing fused-ring acceptor units demonstrate outstanding per-formance in organic solar cells(OSCs)[1−13].We have in-vented highly efficient D-A copolymer donors D18 and D18-Cl by using a fused-ring acceptor unit,dithieno[3′,2′:3,4;2″,3″:5,6]benzo[1,2-c][1,2,5]thiadiazole(DTBT)[1,2].OSCs with D18 or D18-Cl gave power conversion efficiencies(PCEs)of 18.56%and 18.69%,respectively[3,4].Side chain engineering is an effective approach to improve the per-formance of conjugated polymers in optoelectronic devi-ces[14−16].The alkyl side chains not only determine polymers’solubility,but also influence their crystallinity and mobility.In this work,we develop two efficient donors D18-B and D18-Cl-B via side chain engineering on D18 polymers(Fig.1(a)).These donors offer PCEs up to 18.74%(certified 18.2%)in tern-ary OSCs.

Estrogen-mediated downregulation of HIF-1αsignaling in B lymphocytes influences postmenopausal bone loss

In the bone marrow, B cells and bone-resorbing osteoclasts colocalize and form a specific microenvironment. How B cells functionally influence osteoclasts and bone architecture is poorly understood. Using genetically modified mice and highthroughput analyses, we demonstrate that prolonged HIF-1α signaling in B cells leads to enhanced RANKL production and osteoclast formation. In addition, deletion of HIF-1α in B cells prevents estrogen deficiency-induced bone loss in mice.Mechanistically, estrogen controls HIF-1α protein stabilization through HSP70-mediated degradation in bone marrow B cells.The stabilization of HIF-1α protein in HSP70-deficient bone marrow B cells promotes RANKL production and osteoclastogenesis.Induction of HSP70 expression by geranylgeranylacetone(GGA) administration alleviates ovariectomy-induced osteoporosis.Moreover, RANKL gene expression has a positive correlation with HIF1 A expression in human B cells. In conclusion, HIF-1αsignaling in B cells is crucial for the control of osteoclastogenesis, and the HSP70/HIF-1α axis may serve as a new therapeutic target for osteoporosis.

A 2.16 eV bandgap polymer donor gives 16%power conversion efficiency

Nowadays,wide-bandgap(WBG)copolymers attract great attention in the field of organic photovoltaics[1].They are ideal electron-donating partners for low-bandgap small molecule acceptors[2-12].With good energy levels matching,the blend of WBG copolymer donor and small molecule acceptor can harvest most of the sunlight and deliver high power conversion efficiencies(PCEs)in solar cells.PCEs higher than 16%have been achieved[13-15].WBG copolymers especially those with ultra-wide bandgaps(i.e.,optical bandgap(Eg opt)>2.07 eV,absorption onset<600 nm)can find applications in ternary solar cells[16]and tandem solar cells[17].Currently,ultra-WBG copolymer donors are less efficient,generally giving PCEs below 13%[18].Designing highly efficient ultra-WBG copolymers is needed.In this work,we use fluorine-and alkoxyl-substituted benzene(FAB)as the building block to construct ultra-WBG copolymer donors.

Thiolactone copolymer donor gifts organic solar cells a 16.72% efficiency

Since 1995,bulk-heterojunction organic solar cells consisting of one or two organic donors and one or two organic acceptors have been fighting for high power conversion efficiencies(PCEs)and good stability[1].Until recent years,this next-generation photovoltaic technology starts to offer decent PCEs,shedding the light on commercialization,and attracting great attention again[2-14].Compared w让h the continuously emerging highperformance nonfullerene acceptors,high-performance donors are rare.

Interface engineering gifts CsPbI2.25Br0.75 solar cells high performance

Organic-inorganic halide perovskite (ABX3) solar cells (PSCs)have made great progress in recent years [1]. The power conversion efficiency (PCE) has increased up to 25.2%(NREL Best Research-Cell Efficiency Chart, https://www.nrel.gov/pv/cell-efficiency.html, Accessed August 2019). However, they suffer from poor thermal stability due to the volatile A-site organic cations.

The integration structure enhances performance of perovskite solar cells

In recent years,all-inorganic perovskite solar cells(PSCs)have attracted tremendous interest due to their excellent thermal stability[1-3].Unlike organic-inorganic halide perovskites,whose organic component is volatile at temperatures higher than 2000C,all-inorganic perovskites can tolerate temperatures over 400℃without deterioration[4].However,the power conversion efficiency(PCE)for all-inorganic PSCs is much lower than that of organic-inorganic halide PSCs mainly due to its wider bandgap,which leads to limited light absorption and low short-circuit current density(Jsc).At present,the most studied all-inorganic perovskites are CsPbI3 and CsPbI2Br.Partly replacing I with Br can decrease the preparation temperature,but the bandgap will increase[5,6].To improve the performance of inorganic PSCs,many researches focused on crystallinity control and interfacial engineering[7-10].Few works were done to broaden the photoresponse to improve Jsc,thus improving the PCE.Developing tandem or integrated solar cells is an effective approach to make full use of sunlight[11,12].For tandem solar cells,the preparation process is very complicated.